Modern Truck Electrical System 489
ECU may also simultaneously energize the corre- Drive-Axle ABS Event. When the ABS ECU detects
sponding modulator exhaust valve solenoid. This that the wheels on the drive axle are decreasing in
causes the air in the corresponding service brake speed too rapidly, the ABS ECU will signal that a
chamber to be partially vented to atmosphere, reducing drive-axle ABS event is occurring. The signal may be
braking force on the wheel that is nearing lockup. in the form of energizing a low side driver in the ABS
ECU that controls an external ABS event relay. The
The reduction in braking force on the wheel that output of this relay acts as an input to the engine ECM
was nearing lockup as air in the service chamber is and transmission ECU, if applicable. The ABS ECU
vented to atmosphere through the modulator exhaust on newer trucks may instead transmit a J1939 message
port causes the speed of the wheel to increase. The indicating that a drive-axle ABS event is occurring.
ABS ECU then de-energizes the modulator exhaust
and inlet valve solenoids for that wheel. This permits The drive-axle ABS event information is important
compressed air to flow back into the service chamber for the engine ECM and the automatic transmission
to resume normal braking. The process repeats as ECU. The automatic transmission ECU unlocks the
necessary until wheel speed stabilizes. This series of torque converter clutch and disables the transmission
actions of holding and exhausting the air by the sol- retarder, if applicable, when the ABS ECU signals that
enoids occurs very rapidly and can be heard as a series a drive-axle ABS event is occurring. This reduces the
of air venting sounds during an antilock event. load on the torque converter clutch and prevents
the engine from stalling. Two-pedal AMT trans-
The ABS ECU continuously monitors all of the missions may also release the clutch during a drive-
wheel-speed sensors and is capable of independently axle ABS event.
controlling each of the modulator solenoids as neces-
sary to prevent wheel lockup. However, the brakes on The engine ECM uses the ABS event information
the front (steering) axle are usually controlled differ- to disable the engine brake if a drive-axle ABS event is
ently than brakes on the rear axle. A front wheel that occurring. The reason for disabling the engine brake
begins to lock up causes most ABS ECUs to actuate and transmission retarder during a drive-axle ABS
both front modulators at the same time, even though event is that the cause of the drive-axle ABS event
only one wheel may be locking up. This is done so as could be the braking force provided by the engine
not to interfere with steering the truck, which might brake or the retarder, and not due to service brake
occur if only one front brake were applied. However, application. This is especially true when the truck is
some ABS systems with advanced stability features operated on slippery or icy roads. The engine brake or
may control each front brake independently as will be transmission retarder will be engaged once again by
explained later in this section. the engine ECM or transmission ECU after the drive-
axle ABS event has ceased.
Chuff Test. When the key switch is first cycled on,
the ABS ECU performs a chuff test of all of the Automatic traction control (ATC) or anti-spin
modulators. A chuff test is a brief actuation of each regulation (ASR) is optional with most air ABS sys-
modulator coil by the ABS ECU to provide a func- tems. Traction control is used to limit wheel slip under
tional test of the system. The order in which the acceleration. The wheel-speed sensors are used to de-
modulators are chuffed or energized follows a specific termine if the rear wheels are rotating faster than the
pattern, such as clockwise starting at the left front front wheels or if one rear wheel is rotating faster than
modulator. the rear wheel on the other side of the same drive axle.
This would occur if one drive-axle wheel end is in mud
Tech Tip: The chuff test can provide you with or ice and the other side is on dry pavement.
a great deal of information. Depressing the
brake pedal during the chuff test causes air to Traction control can consist of two types of
be exhausted from the modulators when the control, depending on whether one rear drive wheel
modulator inlet and exhaust solenoids are or both rear drive wheels are spinning. When both
tested. This permits you to hear the chuff test rear wheels are spinning, such as when the truck is
during initialization. With experience, you will being operated on snow or ice-covered roads, a re-
learn what a good chuff test sounds like versus quest for torque reduction is transmitted by the ABS
a chuff test where there is a wiring problem or ECU to the engine ECM over the J1939 or J1922 data
a defective modulator. link. The engine ECM responds to the request for
torque reduction by reducing fueling, regardless of
accelerator position. This operation is sometimes
known as engine torque limiting (ETL) or torque-
speed control (TSC).
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
490 Chapter 15
If only one rear wheel is spinning, such as when detects that the traction control switch is in the disable
one wheel is on dry pavement and the other is in mud, position from a switch data link message and transmits
the ABS ECU can use differential braking. Differ- a J1939 message to the ABS ECU to disable traction
ential braking describes the action of the ABS ECU control. The traction control warning indicator in the
applying the brake on the wheel that is spinning to instrument panel is then illuminated via a J1939
cause the differential in the axle to drive the non- message transmitted by the ABS ECU when the trac-
spinning wheel. tion control system is disabled.
During differential braking, an electric solenoid Some trucks may also have a switch for a reduced
contained in the traction control valve is energized to level of traction control that may be called a mud-snow
supply air to the primary brake system relay valve mode, off-road mode, or other similar name. This
(rear brakes) as though the brake pedal had been de- switch does not defeat traction control but provides a
pressed. The normally closed traction control valve is less aggressive reduction in engine torque, permitting
supplied with primary air pressure. The traction con- some wheel slip to occur.
trol solenoid is hardwired to the ABS ECU. When the
ABS ECU energizes the traction control solenoid, air WARNING Differential braking can cause a
is supplied to the rear brake modulators as though the
foot valve (brake pedal) had been depressed. The ABS truck to drive off of a jack stand
ECU then blocks air to the wheel that is not spinning if only one drive-axle wheel end is lifted off the
by energizing the modulator inlet solenoid associated ground and the driveline is operated. Traction
with that wheel. However, the ABS ECU does not control must also be disabled if the truck is operated
energize either modulator solenoid of the wheel that is on a dynamometer.
spinning. The normal state of the modulator causes air
to be supplied to the brake chamber of the wheel that is Advanced Air ABS Features. ABS systems may
spinning. The result is that the rear brake is only ap- also have advanced features to improve vehicle sta-
plied to the wheel that is spinning. This causes the bility. These systems are classified as roll stability
differential in the axle to drive the non-spinning wheel. control (RSC) or electronic stability control (ESC),
with ESC being the more advanced system. These
An indicator lamp in the IPC illuminates steadily advanced features require additional ABS system
or flashes when the ABS ECU detects that a traction sensors, including:
control event is occurring. This indicator lamp in the
instrument panel may be hardwired to the ABS ECU n Steering wheel angle sensor
or controlled by a J1939 message transmitted by the n Air application pressure sensors
ABS ECU. n Air suspension pressure sensor for vehicle load-
Tech Tip: The engine brake or retarder may shift determination
be disabled if the ABS system detects a fault. n Yaw rate sensor that detects vehicle rotation
When diagnosing an engine brake or retarder
issue, check for active ABS DTCs. Addition- (spin) around a vertical axis at the center of
ally, a flashing traction control indicator light gravity as viewed from overhead
does not necessarily mean that there is an ABS n Lateral acceleration sensors (accelerometers)
malfunction. Operators often misunderstand
this feature and may report as a malfunction. Some of these sensors are shown in Figure 15-24.
Using these sensors, the advanced ABS ECU is able to
A means of temporarily defeating the traction control is Courtesy of Bendix Commercial Vehicle Systems LLC.
usually provided. This mode is necessary for dyna- All rights reserved.
mometer testing of a truck and when the truck is driven
in some low-traction situations in which wheel slip is Figure 15-24 Advanced air ABS sensors.
desired. A traction control disable switch in the instru-
ment panel is typically hardwired to the ABS ECU.
On International truck models with a body control
module, the traction control disable switch is located in
one of the switch packs. The body control module
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 491
anticipate that a vehicle rollover, jack-knife, or other Bendix Wingman1 ACB system is also capable of
instability is about to occur and command the engine applying the foundation brakes to increase following
ECM to reduce torque and apply the engine brake or distance or to prevent an impending collision.
retarder via a J1939 message to decrease vehicle
speed. If necessary, the ABS ECU and advanced trailer Future ABS systems will include video systems to
ABS ECU can also automatically apply or release in- alert the truck operator of lane departure and auto-
dividual brakes on the vehicle to attempt to correct the matically apply the brakes if necessary. The video
instability (Figure 15-25). system can also read traffic signs, such as speed limit
signs, and alert the truck operator or even automati-
Advanced ABS features also make use of radar. cally reduce vehicle speed via a J1939 TSC message
A first generation radar system called vehicle onboard transmitted to the engine ECM if the speed limit is
radar (VORAD) was originally produced by Eaton, being exceeded. Nonmetal objects such as animals or
but the technology has since been purchased by Bendix pedestrians can also be recognized by the system and
and has been integrated into the ABS system. VORAD alert the truck operator of the hazard.
is a collision warning system. The system components
are shown in Figure 15-26. The antenna assembly is ABS Warning Lamp. FMVSS 121 requires that an
mounted to the front of the truck and emits radar amber-colored ABS warning lamp must be in clear
microwave pulses that bounce off metal objects in view of the truck operator and that a lamp check must
front of the vehicle. These pulses are used to deter- be performed when the key is first placed in the
mine the relative speed and distance of objects in the ignition position. The ABS warning lamp must also
path of the vehicle. The truck operator display unit illuminate if the ABS system detects a problem that
provides visual and audible indication of objects be- limits the ABS system performance. This also means
ing detected in the path of the vehicle. A blind spot that the ABS warning lamp must illuminate as a truck
sensor is a motion detector mounted to the side of the operator warning even when the ABS ECU is not
truck. Motion detected by the sensor causes the blind powered due to a disconnected ABS power supply
spot display to provide visual indication to the truck connection.
operator.
There are three main methods of controlling the
The VORAD system can also be integrated into the ABS warning lamp. One method of controlling the
vehicle cruise control system to reduce engine torque ABS warning lamp is a directly wired warning lamp as
and apply the engine brake via a J1939 message to shown in Figure 15-27. One side of the ABS warning
maintain a safe following distance. This is referred to lamp filament is connected to an ignition source.
as adaptive cruise control. The latest generation The other side of the warning lamp filament is
Courtesy of Bendix Commercial Vehicle Systems LLC. All rights reserved.
Figure 15-25 Stability control.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
492 Chapter 15
Blind Spot
Display
© Cengage Learning 2014Wiring Harness
Courtesy of Roadranger Marketing. One great drive train from two great companies – Eaton and Dana Corporations.
Central
Processing Unit
Turn Sensor Antenna
Assembly Assembly
Drive Blind Spot
Display Unit Sensor
Antenna
Cable
Figure 15-26 Vehicle onboard radar (VORAD).
12V closed path to ground is also provided for the initial
Ign. ABS lamp test at key-on. If the ABS ECU is not
powered due to a blown fuse or other reason, the
ABS normally closed path to ground is still provided inside
warning the ABS ECU, causing the ABS warning lamp to il-
luminate continuously. This type of system typically
lamp has a shorting clip located in the connector containing
the ABS power supply and ground. The shorting clip is
Shorting Connector designed to be held open by a plastic spacer on the
clip in ABS ECU when the connector is connected to the ABS
ECU. The shorting clip completes a path to ground for
connector the ABS warning lamp if the ABS ECU connector has
been disconnected.
ABS ECU
The second method of controlling the ABS warning
Figure 15-27 Direct-wired ABS warning lamp. lamp is through the use of a fail-safe relay, as shown in
Figure 15-28. The ABS warning lamp is connected to
connected to the ABS ECU. The ABS ECU provides a an ignition source on one side of the filament and the
normally closed path to ground inside the module for normally closed contacts of the ABS fail-safe relay on
the warning lamp if a condition that would cause re- the other side of the lamp filament. The normally
duced ABS performance is detected. This normally closed contacts of the ABS fail-safe relay provide a
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 493
12V illuminate. This type of system is also designed to
Ign. cause the ABS warning lamp to illuminate when
J1939 communications between the ABS ECU and
ABS multiplexed IPC are interrupted or when the ABS
warning ECU is not communicating on J1939. A ‘‘heartbeat’’
message from the ABS ECU is transmitted over the
lamp J1939 data link several times per second indicating
that the ABS ECU is ‘‘alive’’ and capable of com-
86 30 municating a message to illuminate the ABS warning
lamp, if necessary. The multiplexed IPC is designed
Fail-safe to cause the ABS warning lamp to illuminate if the
relay heartbeat message from the ABS ECU is missing for
a period of time.
85 87 87A
Blink code© Cengage Learning 2014WARNING It is important to note the
switch
activation of the ABS warning
ABS ECU lamp when the key switch is first placed in the
ignition position. If the ABS warning lamp fails to
Figure 15-28 Fail-safe relay used to control ABS illuminate for the lamp check, the operational status
warning lamp. of the ABS system cannot be determined. The cause
of the ABS warning lamp check not illuminating for
path to ground. The control coil of the fail-safe relay is the lamp check or remaining illuminated after the
wired to ignition and the ABS ECU. The ABS ECU lamp check should be evaluated immediately.
must energize the fail-safe relay coil for the ABS
warning lamp to be extinguished. The ABS ECU de- Diagnosing Air ABS. The ABS ECU is capable of
energizes the fail-safe relay coil to illuminate the ABS detecting several types of problems that would impact
warning lamp for initial ABS warning lamp check at ABS performance. The modulator circuits and wheel-
key-on and when a condition that causes reduced ABS speed sensor circuits are continuously monitored for
system performance is detected. Disconnecting the open and shorted circuits. Other problems, such as a
ABS ECU connector also causes the fail-safe relay to loose wheel bearing or partially pushed-out wheel-
be de-energized, which results in illumination of the speed sensors, can also be detected by the ABS ECU.
ABS warning lamp. A normally closed momentary If the ABS ECU detects a problem, a DTC can be set
contact blink code switch is often placed in series by the ABS ECU to aid in troubleshooting. The ABS
between the ABS ECU and the fail-safe relay coil. The ECU typically causes the ABS warning lamp to be
blink code switch provides a ground to the ABS ECU illuminated if a DTC is set.
warning lamp output terminal when held in the check-
faults position. The ABS ECU then causes the ABS Legacy Bendix EC15, EC17, and EC30 ABS ECUs
warning lamp to flash out any diagnostic trouble codes may have a series of LEDs on the ECU that is used to
in memory when the blink code switch is returned to indicate a problem that causes a DTC to be set with a
the normal position. This blink code switch may also sensor or modulator circuit without the use of ESTs
be used to temporarily disable traction control with (Figure 15-29). A magnet placed above the reset
some ABS systems by toggling the switch a specific switch located inside these ECUs can be used to clear
number of times. faults and to cause the ECU to reconfigure itself, if
new features are added.
The third method of controlling the ABS warning
lamp is the use of the J1939 data link with a J1939 Most Meritor-Wabco ABS ECUs use an ABS
multiplexed IPC. The ABS ECU communicates warning lamp blink code switch to permit a DTC to
the appropriate J1939 message, indicating whether be retrieved. The ABS warning lamp flashes a spe-
the ABS warning lamp should be illuminated or ex- cific number of times to indicate the DTC number
tinguished. The multiplexed IPC detects this message when the blink code switch is closed and released, as
and causes the ABS warning lamp in the IPC to shown in Figure 15-30. A blink code switch may
also be used on some trucks with Bendix ABS
systems.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
494 Chapter 15
Courtesy of Bendix Commercial Vehicle Systems LLC. TOOLBOXTM is the PC-based diagnostic software
All rights reserved. used to troubleshoot a Meritor-Wabco air ABS system.
These PC-based ABS ESTs permit viewing ABS
Figure 15-29 Bendix ABS diagnostic LEDs. sensor-indicated wheel speed and other ABS-related
inputs. Individual modulators can also be activated to
Most Bendix ABS ECUs also support a small di- assist in diagnosing wiring problems. The ESTs also
agnostic tool called a remote diagnostic unit (RDU) permit the retrieval of DTCs that are inactive but are
that plugs into the truck’s 9-pin diagnostic connector. stored in memory. This diagnostic trouble-code history
The diagnostic tool causes LEDs in the tool to illu- is useful in troubleshooting intermittent ABS com-
minate to indicate a DTC, such as an open left front plaints. The Pro-Link 9000 and other hand-held ESTs
wheel-speed sensor circuit (Figure 15-31). A magnet can also be used to diagnose many legacy air ABS
can also be held near the RDU to cause DTCs to be systems.
cleared, similar to legacy Bendix ABS ECUs.
Diagnosing Wheel-Speed Sensors. The most com-
For more in-depth troubleshooting, Bendix AComTM mon ABS DTCs are those related to wheel-speed
PC-based diagnostic software can be used to trouble- sensors. The wheel-speed sensor is typically installed
shoot a Bendix air ABS system. Meritor-Wabco so that the tip of the sensor is contacting the target. The
distance or air gap between the target and the sensor
has a large impact on the amplitude of the AC voltage
produced by the sensor.
The wheel-speed sensor is typically retained in its
mounting hole by a spring clip for a friction fit. Loose
wheel bearings, brake lining replacement and other
factors can cause the sensor to push away from the
target. Increasing the distance between the sensor and
the low-reluctance target causes the amplitude of the
Blink Code 2-7-0
(left rear wheel speed from drive axle is erratic)
would be displayed as follows:
2.5 2 7 0
sec. flashes flashes flashes
5 sec. 2.5 sec. 2.5 sec. 2.5 sec. 2.5 sec.
pause pause pause pause pause
Switch activated Start 1st digit 2nd digit 3rd digit
here pulse
5.0 sec. pause
Blink Code 2-7-3
(sensor circuit failure on the right rear drive axle)
would be displayed as follows:
2.5 2 7 3
sec. flashes flashes flashes
5 sec. 2.5 sec. 2.5 sec. 2.5 sec. 2.5 sec. © Cengage Learning 2014
pause pause pause pause pause
Switch activated start 1st digit 2nd digit 3rd digit
here pulse
Figure 15-30 Blink codes displayed using ABS warning lamp flash sequence.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 495
Courtesy of Bendix Commercial Vehicle Systems LLC. All rights reserved. socket. The trailer ABS ECU can also receive its power
supply from the trailer stop lamp circuit in the event that
Figure 15-31 Bendix remote diagnostic unit (RDU). the primary power supply via the center pin is inter-
rupted. The seven-way socket ground pin provides the
voltage produced by the sensor to be too low to be ground for the trailer ABS ECU.
detected accurately by the ABS ECU. The low signal
amplitude causes the ABS ECU to set a DTC and Trucks and trailers with air brakes manufactured
illuminate the ABS warning lamp. after March 1, 2001 for use in the United States are
required to have a means to illuminate a trailer ABS
Variable reluctance type wheel-speed sensors can warning lamp in the IPC of the tractor or truck if the
be tested on the truck as shown in Photo Sequence 6. trailer ABS ECU detects a condition that causes re-
duced trailer ABS system performance. The method of
Trailer Air ABS controlling the trailer ABS warning lamp in the IPC is
provided by the trailer ABS ECU injecting a high-
Trailers built for the U.S. market after March 1, frequency signal onto its 12V power supply. The
1998 with air brakes are required to have ABS. The trailer ABS ECU 12V power supply is obtained from
trailer ABS ECU operates in a manner similar to the the tractor via the seven-way trailer socket. This high-
truck ABS system. Trailers have two or four wheel- frequency signal originating from the trailer ABS ECU
speed sensors and modulators. The power supply for is placed onto the tractor’s 12V power supply by the
the trailer ABS ECU is provided through the tractor’s trailer ABS ECU.
or truck’s SAE J560 7-pin trailer socket. Tractors and
trucks that are designed to accommodate a trailer with The truck ABS ECU is designed to detect this
air ABS have a green color-coded trailer socket and use high-frequency signal generated by the trailer ABS
a green color-coded trailer cord identified as ABS. The ECU on its 12V power supply. Through the high-
green color of the trailer socket indicates that the center frequency signal, the truck ABS ECU can determine
pin of the trailer socket is always powered with the key if the trailer ABS ECU has detected a condition that
in the ignition position. The green seven-way trailer causes reduced trailer ABS system performance. This
cord along with an SAE J2394 designation indicates communication method is called power line carrier
that the ground wire, center or auxiliary wire, and stop (PLC). An example of the high-frequency signal that
lamp wire in the trailer cord are of larger gauge than a trailer ABS ECU has transmitted (placed) onto its
standard trailer cords. The larger wire gauge reduces own 12V power supply is shown in Figure 15-32.
the voltage drop on the wiring, providing a higher-level The frequency and phase of the signal is constantly
voltage supply at the trailer ABS ECU. changing. This signal rides on top of the 12V DC
level and typically has peak amplitude of 200mV
The trailer ABS ECU receives its 12V power supply when measured at the voltage supply of the truck
through the center or auxiliary pin of the seven-way ABS ECU. This communication technique is called
spread spectrum and is used to ensure that other
power line noise present in the electrical system does
not interfere with the intended message.
The PLC signal is transmitted as a burst of infor-
mation every half-second by the trailer ABS ECU. The
signal indicates either that the trailer ABS ECU has
detected a condition that is causing reduced ABS
system performance or that it is not detecting any
problems. The phase of each section of the PLC signal
(starting positive or starting negative) is used to rep-
resent logic 1 or logic 0. The combination of logic 1s
1 01 © Cengage Learning 2014
12V
Figure 15-32 Power line carrier (PLC) signal generated by trailer ABS ECU.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
496 Chapter 15
PHOTO Diagnosing a Variable Reluctance
SEQUENCE
6 ABS Wheel-Speed Sensor
© Cengage Learning 2014 © Cengage Learning 2014 © Cengage Learning 2014
PS6-1 Block the vehicle wheels. PS6-2 Raise one side of the axle PS6-3 Disconnect the wheel-
with a floor jack and lower the speed sensor connector.
axle onto a safety stand.
© Cengage Learning 2014 © Cengage Learning 2014 © Cengage Learning 2014
PS6-4 Connect a pair of AC PS6-5 Rotate the wheel at PS6-6 Compare the measured
voltmeter leads to the wheel- 30 rpm (1 revolution per 2 sec- AC voltage to the OEM speci-
speed sensor terminals. onds) and observe the reading fications. Verify the sensor air
on the AC voltmeter. gap is correct, if applicable,
and retest. Otherwise, replace
the sensor and retest.
© Cengage Learning 2014
© Cengage Learning 2014
© Cengage Learning 2014
PS6-7 Reconnect the wheel-speed PS6-8 Raise the axle with a floor PS6-9 Lower the wheel onto
sensor connector. jack and remove the safety stand. the shop floor and remove the
floor jack. Clear the stored DTC.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 497
and 0s is used to signal the status of the trailer ABS electric filter increases the amplitude of the PLC signal
system. at the ABS ECU.
The truck ABS ECU detects the trailer ABS signal Tech Tip: A problem with the trailer ABS
(PLC) in its 12V ignition supply. When the PLC power supply circuit may cause the trailer ABS
signal indicates that a trailer ABS problem exists, the warning lamp to illuminate when the service or
truck ABS ECU causes the trailer ABS warning lamp trailer brakes are applied.
in the IPC to illuminate. Additionally, some trailers
may also have a small amber warning lamp at the left Hydraulic ABS
rear side of the trailer that illuminates if there is an
active trailer ABS DTC. This lamp is visible in the Many medium-duty trucks are equipped with hy-
truck operator’s mirror. A loss of signal from the draulic brakes. ABS has also been required for trucks
trailer ABS ECU also causes most truck ABS with hydraulic brakes built after March 1, 1999, for use
ECUs to illuminate the trailer ABS warning lamp for in the United States. FMVSS 105 defines the re-
several seconds to warn the truck operator that the quirements for hydraulic brake systems. The compo-
trailer ABS ECU is no longer communicating with nents of a typical hydraulic ABS brake system include
the truck ABS ECU. This also occurs when a trailer wheel-speed sensors, a hydraulic brake ABS ECU, and
with PLC is disconnected from the truck at the end a hydraulic control assembly.
of a trip.
The basic function of hydraulic ABS is similar to
The trailer ABS ECU is designed to transmit the that of air ABS except that hydraulic brake fluid is
PLC signal indicating that a trailer ABS DTC is ac- returned to a reservoir during an ABS event. The
tive when power is initially provided to the trailer, valves in the hydraulic control assembly work similar
such as at key-on or when the seven-way connector is to the modulators described in the air ABS section.
first plugged into the trailer. This provides a lamp The electric solenoids and hydraulic valves in the
check of the trailer ABS warning lamp in the truck or hydraulic control assembly are typically installed in a
tractor. single assembly that is bolted directly to the ABS
ECU. An example of a hydraulic ABS system is shown
The trailer ABS warning lamp in the IPC is in Figure 15-33. Note that the normally open inlet
hardwired directly to the truck ABS ECU on some valves and normally closed outlet valves in the hy-
trucks. The truck ABS ECU causes the trailer ABS draulic assembly permit normal non-ABS braking ca-
warning lamp in the IPC to illuminate via hardwire if pability, should the electric portion of the hydraulic
the appropriate PLC signal is detected. The truck ABS system fail.
ABS ECU on International trucks with a body con-
troller transmits the status of the trailer ABS ECU Four-wheel disc brakes are typically used in
over the J1939 data link. If a trailer ABS fault is modern truck hydraulic brake systems. Wheel-speed
detected via PLC, the truck ABS ECU transmits a sensors detect wheel-speed changes in the same way
J1939 message indicating a trailer ABS fault. This as air ABS systems, with the target teeth typically
causes the electronic gauge cluster to illuminate the being cast into the back side of the rotor, as shown in
trailer ABS warning lamp. Figure 15-34.
ABS ECUs designed for straight truck applications Many legacy truck hydraulic ABS systems are not
that are not designed to pull an air brake trailer may capable of J1939 communications, although current
not have PLC capability. If it is ever necessary to re- generations of these systems are SAE J1939 compat-
place an ABS ECU, the replacement ABS ECU must ible. Therefore, hardwired ABS warning lamp circuits
be the correct type for the truck or tractor. It is im- are required for many older trucks with hydraulic
portant to replace the ABS ECU in a truck or tractor ABS. Drive-axle ABS event indication from the ABS
built after March 1, 2001, that is designed to pull an air ECU may also be hardwired to the engine ECM and
brake trailer with an ABS ECU equipped for PLC. transmission ECU.
Otherwise, the trailer ABS warning lamp in the truck
or tractor will not illuminate if a trailer ABS problem Some International trucks with body controllers
exists. The PLC trailer ABS capability is clearly and hydraulic ABS use the body controller for the ABS
marked on applicable ABS ECUs. warning lamp and drive-axle ABS event status. The
drive-axle ABS event and the ABS warning lamp
Some OEMs may utilize a PLC electric filter output from the ABS ECU are hardwired to two body
module which is connected in series with the trailer
ABS power supply circuit. The output of this filter is
part of the ABS ECU power supply circuit. The PLC
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
498 Chapter 15
Figure 15-33 Hydraulic ABS system. © Cengage Learning 2014
© Cengage Learning 2014
ECM and automatic transmission ECU act accordingly,
based on the drive-axle ABS event J1939 message
transmitted by the body controller, causing the engine
brake to be disengaged and the automatic transmission
torque converter to unlock in the same manner as in air
ABS systems.
ABS diagnostic trouble codes can be retrieved on
some Meritor-Wabco hydraulic ABS systems by de-
pressing a blink code switch. This causes the ABS
warning lamp to flash in a sequence that indicates a
two-digit diagnostic trouble code. Meritor-Wabco
TOOLBOXTM is the PC-based EST used to diagnose
problems with the Wabco hydraulic ABS system.
Figure 15-34 Hydraulic ABS disc brake rotor with cast Hydraulic Power Brake. The Meritor-Wabco hy-
tone wheel. draulic power brake (HPB) system introduced in 2004
is significantly different from conventional hydraulic
controller inputs. The body controller detects the ABS brake systems. The HPB system uses two electric pump
warning lamp signal and the ABS event signal and motors to charge two gas-filled accumulators with
transmits the status of the ABS warning lamp and drive- brake fluid under pressure. The two hydraulic systems
axle ABS event over the J1939 data link. The electronic are isolated from each other; one hydraulic system
gauge cluster then illuminates the ABS warning lamp controls the front brakes, and the other system controls
accordingly, based on this J1939 message. The engine the rear brakes. The accumulators and pump motors
are components of the hydraulic compact unit (HCU).
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 499
The HCU also consists of hydraulic valves, a large controlled by a J1939 message for use by a multi-
brake fluid reservoir, and an HPB ECU. A dual master plexed IPC.
cylinder is also a system component. The HPB system
is connected to the J1939 data link. The HPB system also has optional parking brake
control, as shown in Figure 15-35. The thicker lines in
When the brake pedal is depressed to apply the Figure 15-35 indicate hydraulic circuits. The parking
service brakes, a control hydraulic pressure supplied by brake is typically a drum-type driveline brake,
the master cylinder causes hydraulic relay valves in the mounted to the front of the rear axle. The parking
HCU to provide proportionally intensified hydraulic brake is cable-actuated. A spring-applied hydraulically
pressure to the brake calipers. The stored energy of the released (SAHR) mechanical actuator supplies the
brake fluid under pressure in the accumulators is similar energy to apply the parking brake.
to the stored energy in the tanks of compressed air in an
air brake system. Outputs of the HPB ECU for the parking brake are
two high-side drivers to control two hydraulic valves
There is a pressure sensor in each accumulator identified in Figure 15-35 as the supply valve and the
circuit. The HPB ECU monitors the hydraulic system cut-off valve. HPB ECU analog inputs include a di-
pressure in each accumulator and controls the opera- agnosable parking brake control switch. The center-
tion of the pump motors accordingly to maintain both stable three-position parking brake control switch
system pressures at approximately 2320 psi (16 MPa). mounted on the instrument panel has a yellow dia-
If either system pressure drops below 1523 psi mond-shaped knob similar to an air brake system
(10.5 MPa), the HPB ECU transmits a J1939 message parking brake. A parking brake status switch, which
indicating that brake pressure is low. The multiplexed indicates if the parking brake is applied or released, is
instrument panel cluster responds by illuminating the also an HPB digital input.
brake warning lamp and sounding an audible alarm.
This is similar to the operation of the low air alarm in The normal state of the supply valve and cutoff valve
air brake systems. Unlike most other hydraulic brake are such that the parking brake is applied when neither
systems, the force exerted by the operator’s leg muscle valve coil is energized, as shown in Figure 15-35. To
to depress the brake pedal cannot directly apply the release the parking brake, the center-stable three-
brake calipers. The master cylinder output is only a position parking brake control switch, shown in the
control pressure. Therefore, if there is not sufficient center position, is depressed by the operator, similar to
hydraulic pressure stored in the accumulators, the depressing the yellow parking brake knob with air
service brakes cannot be applied. brake systems. This causes a specific value of parking
brake control switch resistance (560O for the example
WARNING Never attempt to drive a vehicle shown in Figure 15-35), which results in a voltage
level at the HPB ECU parking brake control switch
with HPB that has the brake analog input corresponding to a parking brake release
warning lamp illuminated. You may not be able to request. The HPB ECU then switches on the high side
stop the vehicle. driver for the supply valve, which causes brake fluid
under pressure stored in the accumulator to enter the
With the ignition switch in the off position and the SAHR actuator. This causes the piston in the SAHR
vehicle not in motion and brake pedal not depressed, actuator, shown in Figure 15-35, to move to the left.
the system will go into a low power consumption sleep This relaxes the tension on the parking brake cable,
mode and the HPB ECU will cease maintaining the causing the parking brake to release. A Hall effect
brake system hydraulic pressure. The accumulator type parking brake status switch is used by the HPB
pressures will leak down after a period of time, similar ECU to determine the status of the parking brake. A
to air leaking out of storage tanks in air brake systems. magnet on the SAHR piston acts as a target for this
When the ignition is switched on or the brake pedal is switch. With the parking brake applied, the magnet is
depressed, the HPB ECU will awaken and control the directly below the parking brake status switch. When
pump motors as needed to maintain brake system hy- the piston moves to the left to release the parking
draulic pressure. brake, the HPB ECU detects that the parking brake is
released and switches on the high side driver for the
The ABS portion of the system is similar to con- cut-off valve. This causes the brake fluid under pres-
ventional hydraulic ABS and includes ATC and elec- sure to be trapped in the SAHR actuator to maintain
tronic brake force distribution (EBD). EBD adjusts the the parking brake in the released position. The HPB
drive-axle brake apply pressure for more balanced ECU will then switch off the high side driver for the
braking. The ABS control valves (modulators) are supply valve.
located in the HCU. The ABS warning lamp is
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
500 Chapter 15
3k 1k 560
Parking
Brake
Control
Switch
HPB ECU
Brake Return
Fluid Accumulator
Reservoir
Pump Motor Supply
Valve
12V Parking Cut-Off
Brake Valve
Spring Apply Status
Parking Brake Switch SAHR
Actuator
Parking Brake Target © Cengage Learning 2014
Cable Piston
Figure 15-35 Wabco HPB spring-apply hydraulic-release (SAHR) park brake.
The HPB ECU can also use the parking brake the piston shown in Figure 15-35 to move to the right
status switch to determine that the parking brake cable and apply tension to the parking brake cable.
requires adjustment. If the parking brake cable is too
loose, the target will pass by the parking brake status Meritor-Wabco TOOLBOXTM is the EST used to
switch as the parking brake is applied, causing a brief diagnose the HPB system.
transition in the parking brake status switch as the
parking brake is applied. The loose parking brake ca- Repairing ABS Wiring
ble causes the target to rest outside the detection region
of the Hall effect switch; that is, the target is not di- The wiring that connects wheel-speed sensors and
rectly below the parking brake status switch with the modulators to the ABS ECU is typically twisted to-
parking brake applied. gether, as shown in Figure 15-36. The twisting pro-
vides immunity to magnetic field interference that
To apply the parking brake, the parking brake could otherwise induce a voltage difference on sensor
control switch knob is pulled outward from the center- wires that are spaced far apart. With the wires twisted
stable position, which changes the value of the parking together, both conductors are located about the same
brake control switch resistance to 4.56kO. The voltage distance from any magnetic field source. The same
at the HPB ECU analog input causes the ECU to detect amount of voltage should be induced in both sensor
that parking brake apply has been requested by the wires by the magnetic field if the wires are twisted.
operator. The HPB ECU then switches off the high The ABS ECU measures the difference in the voltage
side driver for the cut-off solenoid, which causes the between the two wires of the wheel-speed sensor, and
brake fluid under pressure in the SAHR actuator to not the voltage present on either wire with respect to
return to the reservoir. The spring in the SAHR causes ground. If the same voltage produced by a magnetic
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 501
© Cengage Learning 2014 hours of service (HOS) for each truck operator. An
EOBR can be considered as an electronic logbook.
Figure 15-36 Twisted wiring for ABS wheel-speed Although similar devices known as digital tacho-
sensors and modulators. graphs have been required for many years in EU
countries, EOBRs are not required by the Federal
field is present on both wires, the difference in the Motor Carrier Safety Alliance (FMCSA) as of 2012.
voltage between the two wires due to the magnetic However, proposed legislation will likely require
field is 0V. the devices for new trucks starting in 2014. Some
fleets have already adopted EOBRs as a means of
Some ABS sensor wiring may also be shielded. protecting their compliance, safety, and accountabil-
Shielding is the foil and bare copper drain wire that is ity (CSA) score.
wrapped around wiring to provide immunity to electric
fields, as described in the section on J1939 data link An example of an EOBR is shown in Figure 15-37.
wiring in Chapter 11. The VDO RoadLogTM EOBR produced by Continental
VDO has a touch screen and integrated printer, which
The location of ABS wheel-speed sensors makes produces a printout similar to a paper logbook page.
them vulnerable to wiring harness damage, especially This printout can be presented to a roadside inspector
on front wheels. The ABS wiring must be routed to in the same way as a paper logbook. This system uti-
permit suspension travel and front-axle lock-to-lock lizes a unique USB key, which identifies each specific
steering wheel rotation. Front ABS sensor wiring can truck operator. The key is inserted in a USB port on the
be damaged by contact with the wheel or tire, resulting side of the device when a truck operator change occurs
in cut wiring and an ABS DTC. Even a small cut in to identify the operator. The EOBR then monitors the
ABS wheel-speed sensor wiring can cause a DTC even amount of time that the truck is in motion and logs that
if the circuit remains intact. A small cut in the speed time for the current truck operator. The HOS infor-
sensor wiring or a poorly sealed connector can provide mation from the truck operator key can also be
a leakage path for current to chassis ground when downloaded by the trucking company for record
exposed to water. The path to ground through the keeping. A fleet key can also be inserted in the EOBR
water can be sufficient to cause a DTC indicating a to retrieve information for all truck operators.
sensor circuit that is shorted to ground. The exposure
to water also causes the wiring to rapidly corrode. The EOBR requires a connection to the vehicle
J1939 or J1708 network to acquire vehicle speed in-
formation. Alternatively, an analog input on the device
can be hardwired to a vehicle speed sensor on older
trucks. The EOBR also contains a GPS receiver, which
is used by the device to validate the accuracy of the
vehicle speed signal. The simultaneous input of the
speed sensor signal and the GPS signal ensures that
the EOBR is tamper resistant.
Future versions of EOBRs will permit HOS infor-
mation from the device to be retrieved by fleet man-
agement via a cellular connection.
EMERGING TECHNOLOGIES © Cengage Learning 2014
This section discusses recent advances in truck Figure 15-37 Electronic on-board recorder (EOBR).
electronics. It is likely that future trucks will become
even more complex than current models as rising fuel
costs and increased government regulations require the
trucking industry to become even more efficient.
Electronic On-Board Recorders
An electronic on-board recorder (EOBR) is an
electronic device installed in a truck to record the
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
502 Chapter 15
Telematics emergency alert switch in the truck can also be acti-
vated by the truck operator.
Telematics refers to the integration of tele-
communications and information technology (infor- The application of telematics in trucks is rapidly
matics). General Motors OnStar1 system found in expanding. For technicians, telematics provides the
passenger cars is an example of telematics. In the ability to remotely diagnose problems. Remote diag-
trucking industry, systems developed by Qualcomm1 nostics capability is predicted to greatly expand in the
have been used for several years to track truck and future as telematics matures.
trailer locations. These systems utilize a communica-
tions satellite in a geosynchronous orbit to relay in- Another use of telematics is data mining. Data
formation from the vehicle to the fleet office, as shown mining refers to the use of telematics data by OEMs
in Figure 15-38. Telematics hardware installed in the and fleets for the purpose of prognostics and for
vehicle typically includes the following: antenna, condition-based maintenance. Prognostic is a term
communications modem, J1939 interface module, borrowed from the medical field. Prognostics can be
operator display, and associated cabling. The commu- thought of as predictive diagnostics, or predicting a
nications modem and J1939 interface module are often failure before the failure occurs using the available
combined into an electronic module called a telematics information. You may be tasked someday to replace a
gateway. Placement of these components varies greatly component on a truck that has no truck operator
from system to system and truck to truck. complaints and no DTCs, but the telematics prognostic
system has determined that an impending failure of the
In recent years, several truck manufacturers have component will occur. The impending failure is pre-
begun offering telematics systems that are integrated dicted based on trend analysis (pattern spotting). For
into the truck electrical system and most offer pre- example, fleet history may indicate that a turbocharger
wired options for popular telematics systems. The will likely fail shortly after a compressor surge or stall
communications link for most of these systems is the event has been detected a number of times. Using
cellular telephone network. Providers of these systems telematics data, the turbocharger might be replaced
include PeopleNet1, Teletrac1, and DriverTech1. A and the cause of the surge or stall corrected before a
telematics gateway module connected to one or more catastrophic failure of the turbocharger occurs.
of the truck data links (J1939 and J1708) monitors
DTCs and information such as vehicle speed, fuel Condition-based maintenance (CBM) can refer to
consumption, vehicle mileage, and engine hours. This the use of telematics data to schedule preventative
information can be transmitted back to a central lo- maintenance (PM) based off actual vehicle usage, not
cation to schedule service should a DTC become ac- just miles or hours. Information such as truck operator
tive or to schedule preventative maintenance. habits, primary region of operation, and ambient con-
ditions can be used to either extend or reduce PM
Most of these telematics systems include GPS ca- intervals as compared to hours or miles alone.
pabilities. The location of hazardous cargo can be
monitored by the fleet office and the system can in- Hybrid Electric Trucks
dicate an alert to fleet management if the vehicle is
located outside of a predefined geo-fence area. An Hybrid electric trucks have been introduced in re-
cent years. One of the most widely used hybrid electric
Satellite in
geosynchronous
orbit
Laptop
PDA Internet © Cengage Learning 2014
conduit
Trailer
Provider Application Fleet HQ
Truck access service
uplink provider
Figure 15-38 Satellite link between truck/trailer and fleet management.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 503
truck system is the Eaton electric hybrid. The Eaton Stator HCU
hybrid is classified as a parallel hybrid system. In a
parallel hybrid system, the power produced by the Rotor Trans © Cengage Learning 2014
engine is supplemented by the electric motor under ECU
certain operating conditions. The electric motor is not
typically used alone to propel the vehicle in a parallel ECA
hybrid system, although this is possible with some
parallel hybrid systems. By comparison, in a series Figure 15-39 Eaton electric hybrid AMT cutaway
hybrid system the vehicle is propelled only by an showing motor/generator stator and rotor.
electric motor. The internal combustion engine in a
series hybrid is used to generate voltage to power the The hybrid control unit (HCU) is the central ECU
electric motor. A diesel electric locomotive is similar for the hybrid electric system and controls the inverter
to a series hybrid; many hybrid automobiles are par- and the ECA, as well as many other aspects of the
allel hybrids. system. The transmission ECU is the same found on a
conventional UltraShift AMT, but with modified
The Eaton hybrid system makes use of an Eaton programming.
UltraShift AMT with electronic clutch actuator (ECA),
as shown in Figure 15-39. A three-phase AC motor/ As indicated, the Eaton hybrid system is a parallel
generator is sandwiched between the clutch and hybrid. With the clutch engaged, the rotor of the
transmission. The permanent magnet rotor of the motor/generator and the engine crankshaft rotate at the
motor/generator is splined to the transmission input same speed. During acceleration, the torque produced
shaft. The three-phase stator surrounds the rotor, by the motor/generator acting as a motor and the diesel
similar to the construction of an alternator as discussed engine work together to propel the truck. During
in Chapter 7. braking, the motor/generator acts as a generator to
recharge the batteries (if necessary).
Figure 15-40 shows a block diagram of the Eaton
hybrid system. A conventional diesel engine is the main The inverter is responsible for converting DC
source of power in the system. An UltraShift AMT with voltage supplied by the lithium-ion batteries into a
ECA clutch and integral motor/generator is attached to variable frequency three-phase AC voltage when the
the diesel engine in the same way as a conventional motor/generator is acting as a motor. The inverter is
transmission. The power electronics carrier (PEC)
contains two banks of lithium-ion batteries connected in
series to produce approximately 340V DC. The inverter
is a power electronics component that converts the
340V DC provided by the batteries into a variable-
frequency three-phase AC voltage of up to 500V, which
is connected to the stator windings of the motor/generator.
ECU ECA
Transmission Motor Clutch Diesel
Generator Engine
HCU 500V AC
3-Phase
Power © Cengage Learning 2014
Electronics Inverter
Carrier 340V
DC
Figure 15-40 Eaton electric hybrid functional diagram.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
504 Chapter 15
also responsible for converting three-phase AC voltage (26 kW) continuously. This is not sufficient to power
produced by the motor/generator into approximately the truck down the road at highway speeds, but does
340V DC to recharge the lithium-ion batteries. The provide substantial assist during acceleration result-
inverter is a flux vector drive, meaning it is capable of ing in fuel savings. Trucks used for inner-city deliv-
producing a variable frequency three-phase AC volt- ery can benefit the most from this hybrid technology.
age, like that shown in Figure 15-41. One of the
principles of a three-phase AC motor is that the rota- A variation of the Eaton electric hybrid used in
tional speed of the motor is dependent upon the fre- stationary work truck applications (i.e., bucket trucks)
quency of the AC voltage supplied to the motor. The uses the electric motor to drive the power take off
three-phase voltage produces a rotating magnetic field (PTO). The system shifts the transmission into neutral
around the stator windings, which causes the perma- and releases the clutch to drive the PTO without the
nent magnet rotor to rotate at nearly the same speed as diesel engine running resulting in fuel savings.
the rotating magnetic field. As the frequency of the AC
voltage supplied to the stator increases, the speed of The motor/generator can also act as the starter
the rotating magnetic field also increases, as does the motor for the system, although a conventional starter
speed of the rotor. motor is present in the event the hybrid system is not
functional. The truck can also be operated using the
WARNING Lethal voltage levels are used in diesel engine alone in the event of some hybrid system
failures.
hybrid electric systems. You
should not attempt to work on the high-voltage Future hybrid-electric truck technology includes
components of an HEV until you have had proper the ArvinMeritor hybrid system for class 8 line haul
training and have all the proper protective equip- trucks. At low speeds, the truck is propelled only by a
ment including insulated gloves. High-voltage wir- three-phase electric motor that operates at 700V AC.
ing is identified by orange-colored insulation. Never Voltage for the motor is supplied by a three-phase
splice into this high-voltage wiring. inverter powered by two series-connected 350V
lithium-ion battery packs producing 700V DC. The
The electric motor/generator is capable of producing diesel engine is also used to drive a generator to supply
59 hp (44 kW) of peak power intermittently and 35 hp voltage for the system, like a series hybrid system. At
speeds above 48 mph (77 km/h), the drivetrain tran-
Line 2 sitions to a conventional diesel-powered system with
the electric motor providing power to assist the diesel
Line 1 engine as necessary, like a parallel hybrid system. This
type of hybrid is called a dual-mode hybrid system
Line 3 because it acts as both a series and a parallel hybrid
system. This system consists of two electric motor/
L2 L1 L3 generators and a transmission, which mechanically
shifts the system between series and parallel modes.
The combined system is estimated to produce 480 hp
(360 kW). The inverter powered by the lithium-ion
batteries also provides power for sleeper cab HVAC
systems and cab electrification during overnight rest
stops, similar to an auxiliary generator.
1A © Cengage Learning 2014 TROUBLESHOOTING A MODERN
2A 3A TRUCK ELECTRICAL SYSTEM
3B 2B
The interactions between the various electronic
1B modules on a modern truck should now be apparent to
you. Because of these interactions, an inoperative en-
Figure 15-41 Three-phase AC voltage supplied to gine brake could be caused by a false indication of an
motor windings. ABS drive-axle event being detected by the engine
ECM. This problem could be due to a wiring issue or a
faulty component. The engine ECM inhibits or shuts
off the engine brake by design during a drive-axle ABS
event, as explained in the section on ABS systems.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 505
However, there may be no indication to the truck op- engine OEM now has an online service information
erator of a problem other than the inoperative engine system (SIS). Examples include:
brake. Such a problem would be very difficult to di-
agnose without the knowledge of how the ABS ECU n Caterpillar Service Information System
interacts with the engine ECM to control the engine n Cummins QuickServe Online
brake. n Mack Trucks Electrical Information System
n Navistar Service Information
A different truck that is equipped with an automatic n Paccar DAVIE and ServiceNet
transmission but is not equipped with an engine brake n Volvo IMPACT
might have different symptoms due to a false indica-
tion of an ABS drive-axle event occurring. The truck In general, having no information is typically better
operator might have a complaint of decreased fuel than having the wrong information. For example, using
economy and a higher than normal engine speed at an electrical wiring schematic that does not accurately
highway speeds. The truck operator may also indicate represent the wiring harness on the truck you are re-
that it feels like the truck coasts too fast during de- pairing would likely lead you to the wrong conclusion.
celeration, similar to how a truck with a manual Most of these systems provide the correct specific
transmission feels when the clutch is depressed during service information for the truck being repaired based
deceleration. Again, the cause of all of these com- on the engine or vehicle serial numbers. The manu-
plaints could be a false indication of an ABS drive- facturer can also update online information daily as
axle event due to a wiring or component problem. relevant failures or errors in diagnostic procedures are
When test-driving the truck, a technician would discovered, something that was not possible with paper
probably realize that the lockup torque converter copies of service information. For example, if a man-
clutch is not engaging and is causing all of the truck ufacturer determines from recent warranty history that
operator’s complaints. The transmission ECU is pro- the most likely cause of DTC 123.06 is a short to
grammed to unlock the torque converter clutch during ground at a specific location in the wiring harness, the
an ABS event, as explained earlier. Without this inspection for this failure might become the first step
knowledge about the interaction between the ABS in the troubleshooting procedure for this DTC. This is
ECU and the transmission ECU, a technician might known as case-based reasoning and was introduced in
remove and tear down the automatic transmission, Chapter 4.
looking for a problem with the lockup torque converter
clutch when no such problem exists. Most manufacturers reference the use of proprie-
tary PC-based ESTs in their service information. Prior
Both of these examples illustrate the types of to HD-OBD requirements related to service informa-
problems that technicians may encounter when work- tion availability, some manufacturers would not pro-
ing on modern trucks. One of the most important tools vide their EST or service information outside their
for an electrical troubleshooter to use to solve these dealer network. It remains to be seen how HD-OBD
types of problems is a general knowledge of the op- will affect the independent truck repair facilities since
eration of the entire truck. Every major truck system the ESTs and service information are a considerable
now has some electrical aspects. The interaction expense for a shop that only occasionally services
among the various systems—such as ABS, engine, a particular brand of truck or engine. Additionally,
transmission, and body control module—is increasing HD-OBD only addresses service information related to
as trucks become more complex. Becoming a good emission-related repairs, so ESTs and information
electrical troubleshooter means studying and learning necessary to service a proprietary system such as a
the details of every system on the truck. This may body control module may not be available to inde-
require a considerable amount of self-study on your pendent repair facilities.
own time.
For major components or systems used by several
Manufacturer Service truck manufacturers, such as a Cummins engine, an
Information and Tools Allision transmission, or a Bendix ABS system, ESTs
and repair information can typically be purchased di-
The days of paper service manuals sitting on a rectly from the component manufacturer.
shelf in the office with mostly clean pages have
ended. Electronic service information has become The manufacturer-provided information is the
one of the most important tools for diagnosing and preferred place to start when troubleshooting. How-
repairing modern trucks. Every major truck and ever, too many possible problems can occur on a
modern truck to list every possible troubleshooting
step. In addition to following manufacturer-supplied
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
506 Chapter 15
troubleshooting information, some suggestions for Troubleshooting the J1939 Data Link
troubleshooting modern truck electrical systems are as
follows: This section assumes that the J1939 data link uses
120O terminating resistors at either end of the back-
n Determine if there is anything else that is not bone, as described in Chapter 11. Some J1939 net-
working correctly, not just what the truck op- works may use electronic terminating bias circuits
erator has written up as the problem. Talk to the instead of terminating resistors. A terminating bias
truck operator directly, if possible. Details tend circuit is an electronic device that serves the same
to get lost and the information changes as more purpose as a terminating resistor in a J1939 network.
people are involved in relaying information. However, unlike a terminating resistor the terminating
bias circuit cannot be used to aid in troubleshooting the
n Use an EST to look for DTCs in all electronic J1939 data link, as will be described in this section. If
modules, not just in the module controlling the the truck on which you are working has terminating
system that is not working correctly. For ex- bias circuits instead of terminating resistors, consult
ample, the root cause of what appears to be an the specific OEM information for troubleshooting
engine problem may be due to a problem with procedures.
another electronic module or system on the
truck. The fault history or historical DTCs can The J1939 data link is really just two copper wires
also provide some clues for intermittent prob- covered with insulation and twisted together. The
lems that cannot be duplicated. wires must pass through connectors using terminals
like any other wiring used in the truck electrical sys-
n Look for abnormalities in the data indicated by tem. This means that the data link wiring can fail like
each electronic module using an EST. For the any other circuit, such as a short to ground, a wire-to-
ABS drive-axle event example, the automatic wire short, or an open circuit.
transmission ECU and the engine ECM diag-
nostic tools may provide an indication of an Troubleshooting wiring problems with the J1939
ABS drive-axle event being detected when no data link is usually not too difficult. SAE J1939 uses a
ABS drive-axle event is actually occurring. Most bus-type topology. A bus topology means that there is
ESTs permit the technician to view the status of just a single pair of twisted wires routed past each
various inputs and outputs for a particular elec- electronic module. This pair of twisted wires is called
tronic module, such as the engine ECM. the backbone. Think of the backbone being like Main
Street of a small town. At either end of the backbone, a
n Try comparing data from a truck that has a 120O terminating resistor is connected between the
problem with a similar truck that does not have two conductors (Figure 15-42).
a problem. A mental database of what appears
as normal and what is abnormal data takes Each of the electronic modules splices into each
considerable time to amass. Monitoring data of the wires in the backbone through short sections
from a truck without a problem can assist you in of J1939 cable called stubs. Stubs may also be
determining what abnormal data looks like. Get known as node branch circuits. Think of the stubs as
in the habit of looking at data from the various being like driveways along Main Street. The houses
electronic modules on trucks that are function- are like the electronic modules. One of the drive-
ing correctly. ways or stubs also leads to the 9-pin diagnostic
connector.
n Most ESTs are capable of recording selected
parameters such as ECM sensor input voltages. For troubleshooting purposes, the J1939 data link
This permits a vehicle to be driven while re- can be considered as being just a pair of wires with a
cording data to recreate the conditions that 120O resistor connected across either end. Several
cause an intermittent problem. The recorded modules may be connected to the J1939 data link as
data can then be evaluated for abnormalities well, but they can be ignored for now if the vehicle
after the test drive. batteries are disconnected. Therefore, the J1939 data
link could just be reduced to a pair of wires with a
WARNING Never attempt to monitor EST 120O resistor across the two ends of the pair of
wires, as shown in Figure 15-43. The 9-pin diag-
data while driving a vehicle. Ask nostic connector provides easy access to this pair
a coworker or the vehicle operator to drive if EST of wires.
data must be monitored while the vehicle is
operated. If the truck’s batteries were disconnected, none
of the modules would be able to communicate on
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 507
Engine ABS Trans
ECM ECU ECU
Stub Backbone Stub Stub
Terminating Stub Stub Terminating
resistor resistor
Body Instrument
ECU cluster
© Cengage Learning 2014
Diagnostic © Cengage Learning 2014
connector
Figure 15-42 J1939 bus-type network.
120Ω 120Ω open circuit exists somewhere in the J1939 data link or
one of the terminating resistors is missing. The vehicle
Diagnostic circuit diagram is necessary at this point because the
connector topology or layout of the J1939 data link is important
to know when troubleshooting a J1939 communica-
DIGITAL MULTIMETER tions problem.
MAX MIN One of the unique things about the CAN protocol,
60ΩRECORD which includes J1939, is that there is no single module
% in charge of the J1939 data link. There is no network
HZ router or hub in a CAN network like that in local area
networks (LANs) used to connect many PCs. If the
0 1 23 4 5 6 78 90 J1939 data link were cut into two pieces so that the
engine ECM, transmission ECU, and ABS ECU were
MIN MAX HZ still connected, and the body control module and IPC
were still connected, the two pieces of the J1939 data
mV mA link would each attempt to act like independent CAN
V A networks (Figure 15-44).
V A
Cutting the J1939 data link into two pieces would
A mA A COM V typically still permit the engine ECM, transmission
ECU, and ABS ECU to communicate with each other,
Figure 15-43 J1939 data link modeled as a pair of as in the example shown in Figure 15-44. The body
wires with two 120O resistors in parallel. control module and the instrument cluster would also
still be able to communicate with each other in this
the J1939 data link. With the truck’s batteries discon- example. However, the engine ECM would not be able
nected, a DMM ohmmeter connected across the diag- to communicate with the body control module or
nostic connector CAN+ and CAN– terminals (typically the instrument cluster because of the open circuit in the
pins C and D of the 9-pin diagnostic connector) should J1939 data link. Additionally, an EST connected to the
show the value of the two parallel-connected 120O diagnostic connector would only be able to commu-
terminating resistors. If the entire data link is intact nicate with the instrument cluster and the body control
from terminating resistor to terminating resistor with module. The diagnostic tool that is connected to the
the diagnostic connector located somewhere in be- diagnostic connector would not be able to communi-
tween, the resistance measured across the diagnostic cate with the engine ECM, the transmission ECU, or
connector should be approximately 60O. Two identical- the ABS ECU because of the location of the open
value resistors connected in parallel results in a total circuit in this example.
resistance that is equal to one-half the value of one of
the resistors, as explained in Chapter 2. Therefore, the Because the engine ECM and the automatic trans-
two 120O resistors in parallel as measured at the di- mission ECU can still communicate with each other in
agnostic connector should have approximately 60O of
resistance.
If you measure 120O across the J1939 data link at
the diagnostic connector instead of 60O, then either an
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
508 Chapter 15
Engine ABS Body
ECM ECU ECU
Stub Backbone Stub Stub
Terminating Stub Stub Terminating
resistor resistor
Trans Instrument
ECU cluster © Cengage Learning 2014
Open circuit in Diagnostic
J1939 data link connector
Figure 15-44 Damaged J1939 data link will act as two separate networks.
this example, the open circuit in the J1939 data link link wiring being crushed somewhere and the copper
wiring will probably not cause an automatic trans- wiring piercing through the insulation of both con-
mission shifting problem such as delayed up-shifts. ductors, resulting in a short circuit between CAN+ and
The engine ECM cannot communicate with the mul- CAN–. An ohmmeter connected across the diagnostic
tiplexed instrument cluster, however, because of the connector CAN+ and CAN– terminals with the two
open circuit, so any instrument cluster gauge that re- data link wires shorted together somewhere would
ceives its data from the engine ECM via J1939 will not indicate near 0O.
operate. However, any gauge that receives data from
the body control module would still operate because A defective module somewhere on the truck could
the body control module and the instrument cluster are also cause a short between CAN+ and CAN–. It may
still able to communicate with each other. The J1939 be necessary to disconnect each module one by one to
data link has basically been transformed into two find the defective module. A short between the data
separate communication networks due to the break in link CAN+ and CAN– conductors anywhere in the
the wiring. The single terminating resistor on each half system will cause a loss of communications throughout
of these two networks typically permits sufficient the entire J1939 data link.
communications to occur within each half of the
network. A short to ground of the CAN+ wire will also cause
all communications to cease on the entire J1939 net-
The circuit diagram and a DMM ohmmeter are work. A short to ground of the CAN+ wire would not
very useful in troubleshooting where the break in the cause any fuse to blow because the current flow in the
J1939 data link is located. It may be necessary to CAN+ circuit would be very small. Such a short circuit
disconnect connectors that the J1939 data link is would probably not cause any permanent damage to
passing through to find the source of the problem and any module, either. However, a short to ground of the
use the ohmmeter to determine if the meter can ‘‘see’’ CAN– circuit may only cause intermittent J1939
the resistance of the terminating resistors at either end communication problems.
of the data link. Make sure that the truck’s batteries are
disconnected first, though, because any electronic A short to positive battery voltage of the CAN–
module that is communicating on the J1939 data link circuit will also cause all J1939 communications
will cause voltage pulses to be present across the data to cease. However, a short to battery positive of
link CAN+ and CAN– wires and will affect the the CAN+ circuit will probably only cause inter-
ohmmeter readings. mittent communications problems, or will only cause
some of the electronic modules to not communicate.
Besides an open circuit, other failures can occur Note that either of these types of short can occur
with the J1939 data link that can cause a loss of within any of the electronic modules that are con-
communications between the electronic modules. A nected to the bus, requiring replacement of the
wire-to-wire short circuit between the CAN+ and module.
CAN– wires will cause all communications to cease
on the entire network. This may be caused by the data The voltage measured across the CAN+ and CAN–
terminals of the diagnostic connector—with the bat-
teries connected and the key switch in the ignition
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 509
position so the various modules are communicating— Internal alternator problems, such as failed rectifier
can also tell you a lot about the condition of the J1939 diodes, can result in high amplitude ripple voltage, as
data link. Voltage measurements referenced to ground discussed in Chapter 7. Excessive charging system
from the CAN+ and CAN– with modules communi- ripple voltage can cause a variety of electrical system
cating are also useful for troubleshooting. The exact problems. An oscilloscope or DMM voltmeter set to
voltages measured will depend on your meter and the measure AC voltage can be used to measure charging
truck, but most DMMs in the DC volts setting will read system ripple voltage.
these approximate values with the key switch in the
ignition position: Intermittent open circuits caused by spread ter-
minals or broken wires can sometimes be found using
CAN+ to CANÀ 3V the peak hold mode on a high-quality DMM volt-
CAN+ to ground 2.6V meter. Gently pulling on the wiring harnesses asso-
CANÀ to ground 2.4V ciated with the module in question while monitoring
the voltage using the DMM can cause the intermit-
Voltage readings that vary greatly from these values tent open circuit to be detected by the DMM’s peak
could be an indication of a J1939 data link problem, hold mode.
such as a short to ground, short to +12V, or CAN+ to
CAN– short circuit. Check the simple and obvious things first, even if
it does not seem like there is any possibility of these
An electronic module with a defective CAN being the cause of the problem. Think of it this way:
transceiver chip or a module that is continuously If you cannot find the cause of a problem with a
causing errors to be transmitted onto the J1939 data truck, another technician will have to diagnose the
link can cause communications problems for the entire problem. If the cause of the problem ends up being
CAN network. Each electronic module that commu- something simple that another technician finds in
nicates on the J1939 data link can be removed one by five minutes, your reputation as a troubleshooter will
one (cycle ignition off first) to determine which suffer.
module is causing the communications problem. A
wiring harness problem that causes CAN+ and CAN– At some point, you may have to troubleshoot a
to be reversed at a module connector can also cause problem that another technician could not solve. In
this problem. these situations, it is best to start the troubleshooting
process from the beginning, as though no one else
Tips for Troubleshooters had worked on the truck. Check the fundamental
things yourself, such as B+ power supply, ground,
Troubleshooting a modern truck electrical problem and ignition, even if you have been told that these
can be challenging at times. This section provides have already been checked. Keep in mind that the
some general tips for electrical troubleshooting that previous attempts to diagnose the problem may
you may find useful someday. have caused DTCs to be set that are not related to
the original problem, so treat all stored DTCs as
Most electronic modules require a battery-positive suspect.
(B+) supply, ground, and ignition signals. Series re-
sistance or intermittent connection can cause elec- Technical information is vital for troubleshooting
tronic modules to respond in ways that seem to make most problems. However, documentation such as
no sense, possibly with no DTCs being set by the circuit diagrams or diagnostic procedures may con-
module. The importance of checking the electronic tain errors or may not be exactly like the truck you
module’s power supply cannot be overstated. Open are working on due to changes to wiring that have
circuit measurements of B+ power supply, ground, and not been updated in the circuit diagrams. If some-
ignition at a module connector using a DMM volt- thing you observe in the service information does not
meter can fool even the most experienced trouble- make sense, it may be because the information does
shooter. Ghost voltage can make it appear that the B+ not match the truck you are working on or because of
power supply, ground, and ignition are acceptable an error in the documentation. Read the information
when significant series resistance, commonly known a second time or ask another technician to read the
as green wire, may actually be present in the circuit. information. If applicable, check online for updated
Obtain closed circuit measurements using a breakout information.
box or breakout T whenever possible to minimize
misdiagnosis due to ghost voltage. Diagnostic procedures and other manufacturer-
provided troubleshooting procedures cannot include
every possible cause of a problem. If they could,
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
510 Chapter 15
then skilled electrical system troubleshooters would intermittent open circuits that are very difficult
not be necessary because anyone who can read and to locate. Use breakout boxes and breakout Ts
follow directions could repair any complex electrical whenever possible to avoid damaging connector
system problem. It is often necessary to use the di- terminals. Many OEMs have male terminal pin tools
agnostic procedures to get an idea about what might which can be used to drag-test female terminal
be wrong and use your own troubleshooting skills to sockets.
expand from there when the procedures do not get
you to the source of the problem. One of the most difficult wiring harness problems
to diagnose is multiple-terminal connectors which
DTCs indicate that something is not as expected, have one or more terminal and wire that is not in-
not that some component named in the trouble-code serted in the correct connector cavity (mispinned).
description necessarily requires replacement. Many This typically only occurs on new vehicles, but can
DTCs are caused by intermittent wiring problems. also occur if a new wiring harness is installed or after
Treat a DTC as a general indication of a problem. wiring harness repairs have been performed. In some
Many manufacturers indicate what specific con- cases, two terminals are inadvertently swapped when
ditions must occur to set a specific trouble code. This they are inserted in the connector. The types of
information can be very useful in troubleshooting. problems that this error can cause are nearly unlim-
Many electronic modules record a fault history that ited. Typically, the best way to diagnose two or more
may be retained in memory for a long period of time. swapped terminals in a connector is to use a DMM
This fault history can be analyzed to aid in trouble- to check continuity of each circuit in the suspect
shooting an intermittent problem. Additional infor- wiring harness using the OEM circuit diagrams as a
mation is required for HD-OBD systems, including reference.
the specific conditions required for a DTC to set.
Freeze-frame information may also be valuable for Do not be afraid to ask for assistance when you
troubleshooting. are stumped. The days of one technician knowing it
all without having to use service manuals, online
Occasionally, the fault detection that the manu- information, and circuit diagrams are long gone.
facturer designed may be too sensitive for all oper- Some of the most useful information for newer
ating conditions, such as very cold ambient trucks are technical service bulletins (TSBs) and
temperatures. A warning lamp or DTC that occurs other similar OEM information. These provide in-
intermittently may not be an indication that anything formation on specific problems. Networking with
is actually wrong. Manufacturers may publish field other technicians via the Internet may also be very
information to inform technicians of these known helpful. One such network is the International Au-
problems with fault detection and may offer con- tomotive Technicians Network (iATN), which has a
troller software updates or special procedures to dedicated HD/Fleet forum. Information on this or-
correct these issues. Such manufacturer information ganization can be found in the Internet links at the
can prevent wasted time troubleshooting a problem end of this chapter.
that you cannot solve alone.
Be careful when using ‘‘known good parts’’ from
Sloppy troubleshooting techniques have the po- another truck to troubleshoot. A wiring problem on the
tential to inflict serious damage on the truck’s elec- truck that caused damage to an electronic module such
trical system that may take considerable time and as a shorted to +12V reference ground circuit may
expense for the truck’s owner to correct. The idea of damage the known good module as well. Subtle
troubleshooting is to solve the problem, not create changes, including programming differences between
more problems. One of the worst things that a trou- seemingly identical electronic modules from another
bleshooter can do is to pierce the wire insulation to truck, can also lead you to a wrong diagnosis of the
obtain readings. When the wire is exposed to road real problem.
splash, the wire will corrode in a very brief time and
cause a failure later. This can lead to very expensive Lastly, a $400 DMM and a $2000 oscilloscope are
repairs when some other technician has to find the excellent diagnostic tools, but there is no tool more
source of the problem that you created. valuable for electrical and electronic system trouble-
shooting than a thorough knowledge of the funda-
Another poor troubleshooting practice is to over- mental principles of electricity and electronics. These
probe female terminal sockets. Connector terminals fundamentals include Ohm’s law, Kirchhoff’s laws,
that are probed using too large a test device, such and the rules of series, parallel, and series-parallel
as a DMM test lead, can be spread apart, causing circuits.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 511
Summary
n Allison electronic automatic transmissions use three amplitude of the AC voltage that is generated by the
variable reluctance speed sensors to measure engine variable reluctance sensor.
speed, turbine speed, and output speed. The trans-
mission ECU controls a series of normally open and n Trailer air ABS ECUs may use the power line car-
normally closed solenoids using PWM. These sol- rier technique to signal the truck or tractor ABS
enoids control the flow of transmission fluid to ECU that a trailer ABS fault is active. A variable
apply clutches used for specific range. frequency signal is placed onto the 12V power
supply by the trailer ABS ECU. This signal is de-
n Eaton automated manual transmissions (AMTs) use tected by the truck ABS ECU in its 12V power
two electric motors to actuate the shift mechanism. supply, causing the truck ABS ECU to energize the
AMTs are divided into two-pedal and three-pedal trailer ABS warning lamp on the truck’s instrument
systems, indicating if the clutch is controlled by the panel.
truck operator or the transmission ECU. Inputs to
the ECU include three speed sensors and rail and n Electronic on-board recorders (EOBR) are elec-
gear select positions. tronic truck operator log books designed to record
the hours of service (HOS) for each truck operator.
n Air ABS systems use wheel-speed sensors to de-
termine if wheel lockup is occurring or is about to n In a parallel hybrid system, a diesel engine and
occur. The ABS ECU then controls modulators to electric motor/generator are coupled together. The
block air flowing to the brake chambers and exhaust electric motor is used to supplement the diesel en-
the air out of the brake chambers to prevent wheel gine. In a series hybrid system, the electric motor
lockup. alone is used to propel the vehicle and the engine is
used to drive a generator for the electric motor. A
n Testing wheel-speed sensors and the associated dual-mode hybrid system acts as a series hybrid
circuits may involve raising each wheel end and system during acceleration and as a parallel hybrid
rotating the wheel by hand while watching for the system at higher speeds.
Suggested Internet Searches http://www.conti-online.com
http://www.qualcomm.com
Try the following web sites for more information: http://www.peoplenetonline.com
http://www.allisontransmission.com http://www.iatn.net
http://www.eaton.com
http://www.bendix.com
http://www.meritorwabco.com
Review Questions
1. Which of the following is a true statement for an Allision electronic automatic transmission?
A. Electric motors are used to control the C. The Allison transmission output speed sensor is
clutch packs in an Allision typically directly hardwired to the engine ECM so that
transmission. the engine ECM can determine vehicle speed.
B. It is okay for the engine to crank on a D. The Allison 3000/4000 series 4th Generation Controls
truck with an automatic transmission electronic shifter (truck operator interface)
with the shifter in positions other than communicates with the transmission ECU via the J1939
park or neutral. data link.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
512 Chapter 15
2. Which of the following is a true statement for an Eaton automated manual transmission?
A. On two-pedal versions of AMTs there C. The ECA is controlled by the truck operator using the
is no clutch between the engine and electronic clutch pedal.
the transmission.
D. With no battery power supplied to the transmission
B. On three-pedal versions of AMTs the ECU, the truck operator can still use the shifter to drive
truck operator must control the clutch the truck.
for start-up and when coming to a
complete stop.
3. Which of the following may occur when the ABS ECU detects a drive-axle ABS event?
A. Retarder devices are disabled. C. ABS ECU broadcasts a J1939 message indicating a
drive-axle ABS event is occurring.
B. Automatic transmission lockup torque
converter clutch is disengaged. D. All of the above could occur.
4. Technician A says that automatic traction control can involve the ABS ECU detecting drive wheel spin and
requesting the engine to reduce fueling. Technician B says that automatic traction control (differential
braking) can involve the ABS ECU, causing one of the rear service brakes to be applied. Who is correct?
A. A only C. Both A and B
B. B only D. Neither A nor B
5. The ABS warning lamp is illuminated on a truck with air ABS. Which of the following could be the cause of
the warning lamp?
A. ABS controller power supply fuse is C. ABS controller has detected a fault condition.
blown.
D. All of the above could cause the ABS warning lamp to
B. ABS controller connector has been illuminate.
disconnected.
6. The trailer ABS controller on a trailer with air brakes built after March 1, 2001, controls the trailer ABS
warning lamp in the truck instrument panel through what method?
A. A J1939 message from the trailer ABS C. Fiber-optic cable between the trailer ABS ECU and
ECU to the truck ABS ECU. The trailer ABS warning lamp in the IPC.
truck ABS ECU then causes the trailer
ABS warning lamp to illuminate. D. GFCI-type ground modulation between ABS ECU
ground and trailer ABS ECU ground.
B. The trailer ABS ECU causes a high-
frequency signal to be modulated onto
its power supply circuit. The truck
ABS ECU detects this signal through
its own power supply and causes the
trailer ABS warning lamp to illuminate.
7. The expected resistance between the J1939 data link CAN+ and CAN– measured at the diagnostic connector
with the batteries disconnected on a system using terminating resistors should be approximately what value
of resistance?
A. Infinite resistance; there should be no C. 120O of resistance
path between CAN+ and CAN– D. 60O of resistance
B. Near 0O of resistance
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Modern Truck Electrical System 513
8. An ABS wheel-speed sensor has been pushed partially out of its mounting hole, causing a large air gap
between the sensor and the target. How would the ABS ECU detect that the sensor air gap is too large?
A. The frequency of the signal generated C. The Hall effect device located in the sensor would
by the sensor would be much greater signal the ABS ECU of the reduction in magnetic field
than the other sensors. strength.
B. The resistance of the sensor increases. D. The amplitude of the signal generated by the sensor
would be decreased.
9. A tractor built after March 1, 2001, is being used to pull a trailer with trailer ABS that is also built after
March 1, 2001. Why should a seven-way trailer electrical interconnection cable identified as SAE 2394 be
used with this combination vehicle?
A. The SAE 2394 trailer cable contains C. The SAE 2394 cable contains J1939 wiring for
special electronics that are necessary communications between the trailer ABS ECU and
for the PLC signal. the truck ABS ECU.
B. The power and ground wires are twisted D. Three wires in the SAE 2394 cable are a larger wire
together in the SAE 2394 cable for gauge than a standard cable.
immunity to electromagnetic interference.
10. Which of the following is most likely to cause a no-crank situation on a truck with an Allison 4th Generation
2000 series transmission?
A. The NSBU switch is out of C. The wait-to-start light is still illuminated.
adjustment.
D. An open circuit exists between the transmission ECU
B. The shifter is not connected to the park/neutral indication output terminal and the crank
J1939 data link. inhibit relay or engine ECM neutral input terminal.
11. A voltage of 0V is measured between the CAN+ and CAN– terminals at the diagnostic connector, using a
DMM with the key in the run position. The multiplexed IPC is not operating and several other electrical
problems exist. Of the choices listed, which of the following is most likely a cause of this problem?
A. CAN+ and CAN– are shorted together. C. PLC signal is not present.
B. One terminating resistor is missing. D. VIM module is defective.
12. The ABS warning light does not illuminate in the IPC when the key switch is placed in the ignition position
for a lamp check on a truck that uses a fail-safe relay to control the ABS warning light. Which of the
following would probably not be the cause of the problem?
A. Open circuit between the ABS ECU C. Missing ABS warning lamp fail-safe relay
and the fail-safe relay coil
D. Open circuit between ABS warning lamp fail-safe relay
B. ABS warning lamp is burned out and the ABS warning lamp
13. A particular model of truck with a J1939 multiplexed IPC uses J1939 messages transmitted by the ABS ECU
to control the ABS warning lamp. What would probably be the method used to cause the ABS warning lamp
to illuminate on this truck if the ABS ECU electrical connectors had been disconnected?
A. Shorting clip in the ABS ECU power C. Fail-safe relay detects the missing J1939 messages from
connector provides a ground for the the ABS ECU.
fail-safe relay.
D. The lack of J1939 messages being received from the
B. VIM module provides a PLC signal ABS ECU causes the IPC to illuminate the ABS
indicating that the ABS warning lamp warning lamp.
should be illuminated.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
514 Chapter 15
14. Which of the following is true for an Eaton hybrid electric system?
A. Orange wiring insulation is used to C. The Eaton hybrid electric system is a series hybrid
indicate 12V control circuits. system; the diesel engine drives a generator to supply
voltage to the electric motor.
B. The ECA is controlled by the
HCU. D. The lithium-ion batteries produce 500V AC.
15. What is the best way to troubleshoot a truck electrical problem?
A. Use manufacturer-provided diagnostic C. Use ESTs and other specialized test equipment.
procedures.
D. All of the above may be necessary to find the cause of
B. Use circuit diagrams and other an electrical problem, combined with a strong
information specific to the truck you knowledge of the fundamentals of electricity.
are working on to aid in
troubleshooting.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Glossary
accessory air valve assembly (AAVA) Modular air solenoid automatic traction control (ATC) A means of minimizing
valves utilized in Freightliner multiplexed electrical system. wheel spin during acceleration by the ABS ECU requesting
the engine ECM to reduce fueling if both wheels are spin-
active-high A pulled-down digital input; the input is con- ning or through the use of differential braking if only one
sidered active when a voltage above a specified threshold is wheel is spinning.
present at the input.
backbone The main communications path in a bus-type
active-low A pulled-up digital input; the input is consid- topology. For J1939, the backbone refers to the main section
ered active when a voltage below a threshold is present at of the twisted pair of wires.
the input.
backfeed A condition that exists when current is supplied
aftertreatment Reduction of exhaust emissions outside of to some device in the direction opposite of normal, such as
the combustion chamber. in a dual-filament lamp that has an open ground connection.
Also called feedback.
air management unit (AMU) Air accessory module con-
taining air solenoid valves and switches used in Freightliner base (transistor) The terminal of a bipolar transistor
multiplexed electrical system. that controls the amount of current flowing through a
transistor.
alternating current (AC) A continuous change in the
amplitude and direction of current flow. BCI group number Battery Council International num-
bering system used to describe the dimensions of a lead acid
alternator A voltage generator that produces an alternating battery.
current that is electrically rectified to a DC voltage.
bimetallic gauge A gauge that uses the movement of a
American wire gauge (AWG) A standard indicating the metal strip composed of two different types of metal with
diameter of the conductor in wire. The smaller the gauge different temperature expansion rates. Current flow through
number, the larger the diameter of the wire. a heating element causes the strip to deflect.
ammeter A tool used to measure electric current. An am- binary A numbering system that only uses two characters:
meter is typically part of a digital multimeter. 0 and 1. Also called a base 2 system.
ampere (amp) A unit of measure of electric current flow. bit A single binary character.
One ampere is one coulomb of charge passing a stationary
point per second. blown A fuse that has been subjected to excessive current
and has opened.
analog multiplexing Use of one conductive path by several
parallel-connected switches, each with a different resistance body controller The name of the body control module for
value, that are connected to a single analog input. The voltage International truck models since 2007.
at the analog input is used to determine the switch state.
breakout box A tool used to obtain closed-circuit voltage
analog to digital (A/D) converter An electronic device measurements for troubleshooting, typically at the connec-
that transforms an analog signal into a digital signal. tor for an electronic module.
analogy A comparison of a concept that is understood breakout T A tool designed to obtain closed-circuit voltage
to explain a more difficult concept that is not understood. measurements for a sensor or switch connector.
An analogy always breaks down as the level of detail is
increased. brush A spring-loaded sliding contact device that makes
electrical contact with a rotating component.
anode (diode) The positive material end of a diode.
brushed DC motor A type of DC motor that uses brushes
anti-spin reduction (ASR) See automatic traction con- to provide electrical connection to the armature windings.
trol (ATC).
bucking coil A winding in a three-coil magnetic-type
armature (motor) The rotating component in an electric gauge. The bucking coil’s magnetic field opposes or
motor. ‘‘bucks’’ one of the other coil’s magnetic fields, causing the
gauge to move accordingly.
armature (relay) A movable component in a relay.
bulkhead module (BHM) The main electronic body and
automated manual transmission (AMT) An electroni- chassis control module on the Freightliner M2 truck.
cally controlled clutch/transmission system that uses a
standard mechanical transmission.
515
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
516 Glossary
The BHM is used to control several body and chassis common (terminal) The terminal in a multiple-throw
electrical features and communicates on the J1939 data link. switch or relay that is connected to the movable contact. In a
DIN relay, terminal 30 is the designation for the common
bus A method of connecting the communications lines terminal.
between electronic devices.
commutation A mechanical means of reversing the current
byte A group of eight bits. flow through the armature windings at just the right time to
cause the motor to rotate continuously.
Canadian Motor Vehicle Safety Standard (CMVSS) Col-
lection of laws governing motor vehicles. CMVSS 108 commutator The conductive segments that connect the
addresses lighting requirements. motor brushes to the armature windings.
capacitor An electrical device that stores energy in the composite headlamps Headlamp assemblies that use re-
form of an electric field. placeable incandescent bulbs instead of a sealed beam.
carbon pile A high-power variable resistor used to load a compound-wound A means of winding a motor’s field
circuit for testing. windings and armature windings so that a series-parallel
circuit is formed.
case based reasoning The concept of solving new prob-
lems based on the solution for similar problems in the past. conductance The inverse (reciprocal) of resistance, mea-
sured in units of siemens.
cathode (diode) The terminal of a diode connected to the
N-type material. conductor A material that offers very little opposition to
the flow of electric current. Metals such as copper, iron,
cell A single voltage-producing element in a battery. steel, and aluminum are conductors. Conductors have a
large number of free electrons.
charge A fundamental property of electrons and protons.
There are two types of charge, positive and negative. confirmed DTC An OBD diagnostic trouble code which
Electrons have a negative charge and protons have a posi- the conditions for setting have been detected for two con-
tive charge. secutive drive cycles. This will cause the MIL to illuminate.
Also known as a MIL-on DTC
charging Current flowing into a battery to restore the
chemical energy stored in the battery. connectors Electrical components that hold terminals.
chassis module (CHM) A slave electronic module on the conspicuity Reflective devices required on vehicles by
Freightliner M2 truck used to control several chassis elec- FMVSS and other laws.
trical features. The chassis module receives commands from
the bulkhead module via the J1939 data link. contacts The parts of switches and relays that open to in-
terrupt current flow and close to permit current flow.
chuff test The self-test performed by the ABS ECU when
ignition voltage is first supplied to the ABS ECU. Each control circuit (relay) An electrical circuit that supplies
modulator solenoid is actuated in a specific sequence during voltage to the relay coil.
the test.
controller area network (CAN) A group of electronic
circuit A complete path for the flow of electric current. modules that communicate with each other without the need
for a master controller.
circuit breaker A thermal circuit protection device. There
are three SAE classifications of circuit breakers. conventional theory The assumption that the flow of cur-
rent is from positive to negative. Conventional theory de-
circuit protection device (CPD) Circuit protection device, scribes the movement of the holes or spaces, which is in the
such as a fuse, a circuit breaker, or a fusible link. The CPD is opposite direction of the electrons.
used to protect the wiring harness from excessive current flow coulomb The charge associated with 6.25 Â 1018 electrons.
in the event of a failure such as a shorted to ground circuit.
counter emf (CEMF) Counter electromagnetic force,
clearance lamps The lamps that are located at the top voltage that is produced by a motor, per Lenz’s law, that
corners of the front and rear of the truck or trailer. acts as series-opposing to the voltage supplying the motor.
CEMF is the reason that a motor draws less current as motor
clipping A means of attaching a wire harness to the truck. speed increases.
clockspring A device used to permit electrical contact be- covalent bond A chemical bonding where pairs of valence
tween switches in the steering wheel and steering column. electrons are shared between atoms.
closed loop control An automatic control system in which current The flow rate of electrons measured in amperes.
a process is regulated by feedback. The process being
controlled is measured, which is compared to the desired data link The common name or slang for a twisted pair of
outcome. The control system adjusts accordingly to achieve wires used to connect a group of electronic modules.
the desired outcome.
data mining The use of telematics information for prog-
cold cranking amps (CCA) A battery rating that indicates nostics and machine usage information.
how much current a new fully charged battery can provide
continuously for 30 seconds at a temperature of 08F and still daytime running lights (DRL) Front-mounted lamps that
maintain a terminal voltage greater than 1.2V per cell (7.2V are illuminated any time a vehicle is being operated. DRL
terminal voltage for a typical 12V truck battery). are sometimes reduced-intensity low-beam headlamps.
collector A terminal of a bipolar transistor. delta A method of connecting three phases of an alternator
stator end to end so that a triangle or delta shape is formed.
combination stop/turn A red-colored turn lamp at the rear
of a vehicle that also acts as the stop lamp.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Glossary 517
derate Intentional reduction of maximum engine power by earth Another name for chassis ground, commonly used
the engine ECM to protect the engine due to a detected outside of the United States.
malfunction. Also refers to the reduction in engine power
due to an exhaust emissions system failure. EEPROM An acronym that stands for electrically erasable
programmable, read-only memory, memory that can typi-
desired output In control system theory, the set point es- cally be erased and rewritten in small sections.
tablished by the controller.
electric field Invisible lines of electric force that exist be-
diagnosable switch A special type of switch typically used tween positively and negatively charged objects.
in a critical circuit that contains a resistor network. Switch
contacts in parallel with the resistors short out specific re- electric shock Electric current flowing through the body,
sistors, causing the resistance measured between the ter- causing involuntary muscle action.
minals of the switch to change with the switch opened and
closed. A diagnosable switch is connected to an analog electrical potential A quantity of electrons held at a dis-
input. tance from a quantity of protons. Electrical potential is also
called voltage.
diagnostic trouble code (DTC) A number sequence as-
signed by an OEM or by SAE to indicate that a specific electrical system controller (ESC) The name given to the
diagnostic condition has been detected. body control module in International high performance
truck models up to 2007.
dielectric Nonconductive insulator material placed be-
tween the plates of a capacitor. electrolyte A substance that mixes with water to form a
solution or mixture that conducts electricity. In a lead acid
differential braking An action of the ABS ECU that battery, sulfuric acid and water make up the electrolyte.
causes the brake to be applied on a wheel on one side of a
drive axle that is spinning due to low traction. electromagnet A magnet that is formed when current flows
through a conductor.
digital Devices or circuits in which the output varies in
distinct (whole) steps. electromagnetic interference (EMI) The disturbance caused
by electrical and magnetic fields. EMI can cause electrical
digital multimeter (DMM) A portable handheld diagnos- noise to be present in signals, resulting in unexpected
tic tool consisting of a voltmeter, ammeter, and ohmmeter in actions.
one tool.
electromotive force (EMF) The force that produces the
diode A semiconductor device that permits electric current flow of electrons in a circuit, another name for voltage.
to flow in only one direction.
electron A subatomic particle with a negative charge that
diode trio Three diodes placed in a single package, used to orbits the nucleus of an atom.
rectify the voltage output of the three-phase stator. The
output of the diode trio is used to supply the current for the electron theory The assumption that current flow is from
rotor field. negative to positive. Electron theory describes the actual
direction of movement of electrons.
DIP switch Dual in-line package switch, a series of small
switches that are often used in electronic gauge clusters for electronic control unit (ECU) The generic name of an
programming the vehicle pulses-per-mile and pulses-per- electronic module such as ABS. The engine control module
revolution values for the speedometer and tachometer. may also be called an ECU by some OEMs.
direct current (DC) Electric current that does not change electronic gauge cluster (EGC) The name of the multi-
amplitude or direction. plexed instrument panel cluster on International multiplexed
vehicles.
discharging Current flowing out of a battery, the chemical
energy being converted into electrical energy. electronic on-board recorder (EOBR) Electronic log
books which monitor driver hours of service information.
doping The addition of impurities to silicon to form a
semiconductor. electronic service tool (EST) Term used to describe a
broad range of diagnostic tools, including PC-based OEM
drain A terminal of a field effect transistor (FET). diagnostic programs and handheld scan tools.
drive (motor) The device that contains the overrunning electronics The control of electrons using electricity.
clutch and pinion gear on a cranking motor.
emitter A terminal of a bipolar transistor. Current flows from
drive axle ABS event The lockup or impending lockup of a the base to the emitter and from the collector to the emitter.
wheel on a drive axle; used to cause the engine brake to be
disabled and the lockup torque converter clutch to be energized (relay) A relay coil that has current flow, cre-
disengaged. ating an electromagnet.
dual-filament lamp An incandescent lamp that contains energy The capacity or ability to perform work.
two filaments. The two filaments share a common ground
connection, making the lamp a three-terminal device. equivalent resistance A single resistance that is used to
represent the total resistance of a group of resistors con-
dual-mode hybrid system A type of hybrid electric vehicle nected in series, in parallel, or in some other arrangement.
that has characteristics of both a series and a parallel hybrid
electric vehicle. error (control system) The difference between the desired
output and the measured output in an automatic control system.
duty cycle The ratio of the time on to the total cycle time,
expressed as a percentage. excitation The supply voltage required to activate a circuit.
When referenced to an alternator, a rotor that is supplied
with voltage and is forming an electromagnet.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
518 Glossary
exhaust gas recirculation (EGR) The rerouting of exhaust ground fault circuit interrupter (GFCI) Fast-acting cir-
gas back into the combustion chamber for the purpose of cuit breaker, used to help protect against electric shock by
reducing peak combustion temperature to reduce the for- comparing the current in the hot conductor against the
mation of oxides of nitrogen. current in the neutral conductor.
failure mode indicator (FMI) SAE J1939 and J1708 two- growler A tool used to determine if motor armature
digit identifier used in a DTC to describe the type of failure windings are shorted together.
that has been identified.
Hall effect A voltage produced in a thin layer of semi-
Federal Motor Vehicle Safety Standard (FMVSS) Col- conductor material when it is exposed to a magnetic field.
lection of U.S. laws governing motor vehicles. FMVSS 108 The voltage is proportional to the strength of the magnetic
addresses lighting requirements. field.
feedback See backfeed. halogen A noble gas used in incandescent lamps to prevent
tungsten from depositing on the interior surface of the lamp
field effect transistor (FET) A voltage-controlled transistor. glass.
field coil The windings that cause the motor pole shoes to hardwire The use of conventional wiring as a means to
become electromagnets. connect electrical devices.
field diode Another name for a diode trio in an alternator, harness A modularized section of wires designed to be
used to self-excite the rotor field. connected to other harnesses or to electrical components
such as switches and lights.
flash memory Digital memory that can be erased and re-
written in large sections. Program memory for an electronic H-bridge A method of using four transistors to reverse the
module is typically contained in flash memory. polarity of the voltage supplied to an electric motor to re-
verse the direction of rotation of the motor.
floating An electronic device input terminal that is not
connected to anything outside of the electronic module. heavy duty on-board diagnostics (HD-OBD) U.S. EPA
regulated diesel exhaust emissions; the ability of an engine
forward-biased A diode that is conducting electric current. system to detect that the tailpipe exhaust emissions are
outside of permissible levels and provide indication to the
free electron An electron that can be easily dislodged from vehicle operator of the condition.
an atom.
hertz A unit of frequency, cycles per second.
freeze frame Parameters such as engine coolant tempera-
ture stored in an electronic module’s non-volatile memory high intensity discharge (HID) A type of headlamp sys-
when a DTC became active. tem that uses an electric arc between tungsten electrodes as
the means of illumination.
frequency The number of complete cycles per second of a
repeating waveform, measured in hertz. high side driver A transistor used as a switch or relay that
supplies a connection to a positive voltage source. High side
fretting corrosion Referring to electric terminals, a layer drivers can supply 20A or more of current.
of insulating oxide material caused by micro-movement
between mated terminals. The movement wears away the HVAC An acronym that stands for heating, ventilation, and
terminal plating material, leaving the base metal of the air conditioning.
terminal to corrode when exposed to oxygen.
hydraulically actuated unit injector (HEUI) An elec-
full-field A rotor winding that is supplied with unregulated tronically controlled diesel fuel system used by Navistar and
positive voltage and ground. A method of determining if a Caterpillar. High-pressure engine lubrication oil is used to
voltage regulator is defective, typically not performed on- produce fuel injection pressures within the unit injectors.
vehicle with electronically controlled fuel systems. Hydro-MaxTM A hydraulic brake booster system produced
by Bosch that utilizes an electric pump motor to provide
fuse A circuit protection device, designed for one-time use, brake force amplification in the event of a stalled engine or
in which an element made of a conductive material is other loss of power steering flow.
designed to melt to open the path for current flow when
subjected to excessive current. hydrometer A tool used to measure the specific gravity of
battery electrolyte, engine coolant, and diesel exhaust fluid.
fusible link A circuit protection device composed of a
length of wire with a special insulation material designed identification lamps Three lamps centered on the front of
not to ignite (sustain a flame). the truck at the top edge of the cab, at the rear on the top
edge of the box of a van truck, or at the rear of the top of the
gate A digital electronic hardware device used to make trailer at the center. Identification lamps are amber at the
logical decisions. In field effect transistors, the control ter- front of a vehicle and red at the rear of the vehicle.
minal of the transistor.
impedance A measure of the opposition to the flow of
gear-reduction A type of starter motor that utilizes a current in an electrical circuit. Impedance is measured in
planetary gear set to reduce the motor speed and increase units of ohms and differs from resistance in that the AC
torque output. effects of capacitive and inductive reactance are included.
ghost voltage The voltage that is dropped on the internal idle validation switch (IVS) A switch used in conjunction
resistance of a digital multimeter when an open circuit with the accelerator position sensor to verify that the ac-
measurement is obtained on a circuit with a high level of celerator is being depressed by the operator.
series resistance present somewhere in the circuit.
ground The metal components of the vehicle that are
connected to the negative battery terminal.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Glossary 519
incandescent lamps Sealed electric lighting devices that ISO symbol International Standards Organization, a graphic
contain a thin piece of wire called a filament. Electric cur- symbol used to designate warning and indicator lamps such
rent passing through the filament causes it to glow and give as high-beam headlamps, oil level, and coolant temperature.
off light.
J1587 An SAE standard that defines the message structure
induced The voltage that is produced from the cutting of used in a serial communications network.
magnetic lines of force by a conductor.
J1708 An SAE standard that defines the physical data link
inductor A coil of wire that produces a magnetic field wiring and hardware used in a serial communications network.
when current flows through the wire. Together with J1587, J1708 is known as the ATA data link.
injection control pressure (ICP) HEUI fuel system high- J1939 A series of SAE standards that defines the message
pressure engine lubrication oil pressure. The high-pressure structure and hardware for a high-speed serial communica-
engine oil is used within the electronic injectors to develop tions network. SAE J1939 describes a controller area net-
the fuel injection pressures. work (CAN).
injection pressure regulator (IPR) HEUI fuel system JFET Junction field effect transistor (FET), the simplest
control solenoid used to regulate the injection control type of FET. The JFET is controlled by the difference in
pressure. voltage between the gate terminal and the source terminal.
in-range failure A type of electric failure where the volt- junction The location where positive semiconductor ma-
age supplied by a sensor to an electronic module is within terial makes contact with negative semiconductor material
the normal operational range of the sensor, but does not to form a device such as a diode.
reflect correctly the actual physical parameter being mea-
sured. No DTC for out of range high or low would be set Kirchhoff’s current law A fundamental principle of
due to this type of failure. In-range failures can be caused by electricity that states that the algebraic sum of current
resistance in the wiring harness or failed sensors. flowing into a junction must be equal to the algebraic sum
of current that flows out of the junction, also known as
in-rush current A high level of current that flows when a Kirchhoff’s first law.
device such as a light or motor is first supplied with voltage.
The current decreases rapidly as the device reaches normal Kirchhoff’s voltage law A fundamental principle of elec-
operating conditions. tricity that states that the sum of the voltage drops measured
across devices in a closed loop must be equal to the alge-
instrument cluster unit (ICU) display Multiplexed in- braic sum of the voltage sources, also known as Kirchhoff’s
strument panel cluster used on the Freightliner M2. The ICU second law.
communicates with other electronic modules on the truck
via the J1939 data link, and has hardwired inputs from the latching (switch) A switch that remains in the last position
multifunction stalk switch. to which it has been moved.
instrument panel cluster (IPC) A generic term for a group leakage current A small amount of current that flows
of gauges and warning lamps that provide the operator with through an electrical or electronic device when the device is
information such as vehicle speed. switched off or is otherwise not conducting.
instrument voltage regulator (IVR) A legacy electric learn cycle A calibration of an actuator, also known as zero
component used to supply a regulated voltage for a bi- and span calibration. The zero point is the minimum posi-
metallic gauge. tion (typically closed) to which a device controlled by an
actuator can be driven (i.e., fully closed). The span is the
insulation The nonconductive material, such as cross- measurement from the zero position to the maximum posi-
linked polyethylene, that surrounds a conductor. tion (i.e., fully open).
insulator The materials that offer a great deal of opposition Lenz’s law A fundamental law of electromagnetism that
to the flow of electric current. The amount of current describes the polarity of the voltage self-induced in a coil as
flowing through an insulator can typically be ignored be- being opposite to the polarity of the applied voltage.
cause it is so small. Materials such as glass, plastic, and
paper are insulators. license lamp White light that is located above the license
plate at the rear of the vehicle, often incorporated into the
integrated circuit A circuit in which the transistors, di- tail lamp assembly.
odes, resistors, and other components are formed during the
process of manufacturing the device. Integrated circuits are light emitting diode (LED) A semiconductor device that
commonly called chips. gives off visible or invisible light.
interlocks The means of preventing an unsafe or un- linear Hall effect sensor A type of non-contact position
expected action from occurring, such as the release of sensor that measures the strength of a magnetic field to
sliding fifth wheel lock in a vehicle traveling at high speeds. determine the location of the target magnet relative to the
sensor.
internal resistance The total resistance between the ter-
minals of a battery. Internal resistance increases as the linear power module An electronic device used to control
battery’s state of charge decreases. blower motor speed by introducing a transistor-controlled
series resistance to the circuit.
ion An atom or molecule in which the total number of
electrons does not equal the total number of protons, giving liquid crystal display (LCD) A type of alphanumeric
it a net positive or negative electrical charge. display that uses a liquid to display information. A voltage
applied to the liquid causes the liquid to darken.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
520 Glossary
load A device through which electric current flows, such as momentary contact A switch that is spring-loaded in a
a resistor, that changes electrical energy into another form specific position. Moving the switch, such as by depressing
of energy. it, causes the switch to open or close. Releasing the switch
causes the switch to return to its normal state.
load dump The dissipation of electrical energy when an
electric load is suddenly disconnected from a generator. MOSFET Metal oxide semiconductor field effect transistor,
Load dump can cause the charging system voltage to in- a type of transistor that is often used as a high-current switch.
crease to 50V or more and stay at a high level for 100 ms or
more. The result is potential damage to electronic compo- multifunction switch Turn signal stalk-mounted switch
nents. Load dump is typically caused by disconnecting that may include switches for several other features. For
battery cables with the engine running. Freightliner M2 models, the multifunction switch contains
resistive ladder-type switches, which are used to control the
lookup table Stored information used by a microprocessor windshield wipers, and a headlamp dimmer switch.
to determine how it should control an output based on inputs.
multiplexing The methods used to combine more than one
logic The use of correct or valid reasoning to come to a channel of information into a common signal path.
conclusion.
negative temperature coefficient (NTC) A reduction in
low side driver A transistor used as a switch that supplies a the resistance of a material as the temperature increases.
connection to ground.
negative voltage spike The high-amplitude reverse-polarity
magnetic gauge A type of gauge that uses the principles of voltage induced in a coil when a magnetic field surrounding
electromagnetism to cause the gauge pointer to move. the coil collapses; this happens when current flow through
the coil is interrupted.
magnetic lines of force The imaginary lines used to
quantify the strength of a magnetic field. The arrows on the no-load voltage The voltage measured across the terminals
lines indicate the direction in which the needle of a compass of a battery with no current flow present in the circuit. The
would point if placed in the magnetic field. no-load voltage is an indication of the battery’s state of
charge.
malfunction indicator lamp (MIL) On-board diagnostic
(OBD) regulated warning lamp that illuminates when a nonlinear A term from mathematics that describes a sys-
condition that causes the exhaust emissions to be out of tem where the result (output) is not proportional to the
compliance is detected. causes (inputs). For example, many electronic devices such
as thermistors are nonlinear devices. A thermistor with a
marker lamps The amber and red lamps located on the negative temperature coefficient might have a resistance
sides of the truck and trailer. change of only 10O when the measured temperature de-
creases from 808F to 708F and a 10,000O resistance change
material safety data sheet (MSDS) A document that when the measured temperature decreases from À208F to
contains information about the potential health hazards of À308F. The mathematical equation describing the behavior
exposure to potentially dangerous substances, and safe of a nonlinear system has terms that contain an exponent or
procedures to use when handling these substances. power other than one. Plotting a nonlinear equation on a
graph would result in a line that is not straight. By com-
measured output Closed-loop control system measure- parison, a linear equation contains only terms that have
ment of the process being controlled. In a home heating exponents of one (an exponent of one is typically not
system, the thermostat setting is the set point or desired shown). Plotting a linear equation on a graph would result in
output. The measurement of the actual room temperature is a straight line.
the measured output.
non-volatile memory Digital memory that is maintained
measurement error Term describing an in-range sensor through power disconnection.
failure. An example is an indication of high coolant tem-
perature being caused either by coolant temperature that normal state The condition of the contacts on a relay or
actually is too high or by a false measurement of the coolant momentary-contact switch when the relay is not energized
temperature by a sensor or sending unit. The latter is mea- or the switch is in the relaxed position.
surement error.
N-type Semiconductor material such as silicon that is
message identification (MID) SAE J1587/J1708 designa- mixed with impurities to produce a material with an excess
tion of the electronic module or system that has detected a of electrons.
failure or the device that is sending specific information.
ohm A unit of measurement of resistance, named after
microprocessor A device that processes information in a Georg Simon Ohm. One ohm is the amount of resistance
digital form. necessary to cause one ampere of current to flow when one
volt of potential is applied across the resistance.
microswitches The small switches that are typically con-
tained in a sealed package designed to carry a low level ohmmeter A tool used to measure electrical resistance,
current. typically part of a modern digital multimeter.
milling The process in which the pinion gear and ring gear Ohm’s law A fundamental principle of electricity that de-
remove material from each other when the pinion gear does scribes the relationship between voltage, current, and re-
not achieve full engagement with the ring gear. sistance in a mathematical form.
modulator A component of an air ABS system, an elec- one-way clutch Also called an overrunning clutch, a means
trically controlled valve designed to block the flow of air to of permitting the pinion gear to rotate faster than the motor
a brake chamber and to exhaust the air in the chamber
through two separate solenoids.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Glossary 521
when the engine starts and the pinion gear is still in mesh it will be erased by the ECM after three consecutive drive
with the ring gear. cycles without the problem being detected. A permanent
DTC cannot be cleared by an EST.
open circuit An interruption in the path of electric current.
An open circuit has an infinitely high resistance. permanent magnet A magnet that remains magnetized
without an external magnetic field present. Small motors
open loop control Non-feedback control, a controller that often use permanent magnets for the pole shoes.
determines its output based on current operating state and the
program instructions. The controller does not monitor the phase The angular relationship between two waveforms
actual output of the system. Failure of important sensors in an that are plotted in reference to time; also a winding of a
otherwise closed loop control system can cause the system to generator or a transformer.
go into open loop control as a means of still permitting the
system to operate, but at a reduced level of performance. pinion gear A small diameter gear driven by the cranking
motor that meshes with the engine ring gear.
original equipment manufacturer (OEM) Generic term
for manufacturers of vehicles and major vehicle systems plates Grids with pasted-on lead. Lead acid batteries have two
such as engines. different types of plates—positive plates and negative plates.
oscilloscope A diagnostic tool used to observe a changing pole (switch) The number of independent circuits that can
voltage or current referenced to time. be controlled by a switch. This can also be thought of as the
number of movable contacts contained in the switch or the
out of range high (ORH) A condition that exists when the number of switch input terminals.
voltage measured at an input of an electronic module is
greater than the maximum expected amount. pole shoe The magnets that set up the stationary magnetic
field in an electric motor.
out of range low (ORL) A condition that exists when the
voltage measured at an input of an electronic module is less positive engagement A type of cranking motor that does
than the minimum expected amount. not permit the motor to begin rotating until the pinion gear
is in mesh with the ring gear.
overrunning clutch See one-way clutch.
positive temperature coefficient (PTC) A material in
oxides of nitrogen (NOx) Regulated engine exhaust emis- which an increase in temperature causes an increase in the
sion, includes NO and NO2. NOx is formed in the combustion resistance of the material.
chamber, especially at high temperatures. NOx is controlled
in-cylinder by reducing peak combustion temperatures using potential The capability of doing useful work.
EGR or is converted in the exhaust system (aftertreatment) by
use of selective catalytic reduction (SCR). potential energy Stored energy measured in joules. There
are several types of potential energy, including gravita-
parallel (connection) A means of connecting two or more tional, spring, and chemical.
devices so they all have two common connection points.
potentiometer A variable resistor that is often used as a
parallel circuit A circuit that has more than one path for position sensor. A potentiometer is a three-terminal device.
electric current to flow through. Components that are con- Two terminals are connected to each end of a resistive
nected in parallel all have a common voltage drop. element and a third terminal is connected to a wiper contact.
The output is a variable voltage depending upon the position
parallel hybrid system A type of hybrid electric vehicle in of the wiper contact.
which the power produced by the prime mover (i.e., diesel
engine) is supplemented by an electric motor. power The rate at which work is performed or the rate at
which energy is transformed from one form to another. The
parameter group number (PGN) SAE J1939 numerical unit of measure of power is the watt.
designation of a group of related parameters contained
within one 8-byte CAN message. power line carrier (PLC) The use of a high-frequency
signal added to the power supply DC voltage for commu-
parameter identifier (PID) SAE J1587/J1708 defined nu- nications between devices. This is specifically used in
merical designation of a specific measurement, such as modern trailer ABS systems to signal the truck ABS ECU of
engine coolant temperature. a fault detected by the trailer ABS ECU.
parasitic loads The current draws that occur with the key previous MIL-on DTC OBD exhaust emissions related
switch in the off position. diagnostic trouble code, a DTC for which the conditions for
setting the DTC and illuminating the MIL had occurred in
parking lamps The amber or white lamps located at the the past. Previous MIL-on DTCs are erased by the ECM
front of the truck. after 40 engine warm-up cycles provided the problem is not
detected again.
particulate matter (PM) U.S. EPA regulated diesel ex-
haust emission. PM is mostly carbon compounds (soot) that programmable parameter Rewritable non-volatile mem-
make up black smoke, but PM also includes other forms of ory section of an electronic module, which contains data
visible exhaust smoke. unique to a vehicle or engine, or owner preferences.
pending DTC OBD exhaust emissions related diagnostic proportional solenoid An electric solenoid that can be
trouble code, a DTC for which the conditions for setting the driven and held in a desired location within a range of po-
DTC have been detected for one drive cycle. sitions, not just the extreme ends of travel such as a standard
electric solenoid.
permanent DTC OBD exhaust emissions related diagnos-
tic trouble code, indicates that a confirmed DTC had been proton Subatomic particles that, together with neutrons, make
set in the past. A permanent DTC is not actually permanent; up the nucleus of an atom. Protons have a positive charge.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
522 Glossary
P-type A semiconductor material such as silicon that is Residual magnetism is necessary to cause the alternator
doped with impurities to form a material with a deficiency initially to produce enough voltage to supply the current to
of electrons. the field.
pull-down resistor Part of an electronic module input cir- resistance The opposition to the flow of electric current.
cuit, a resistor that completes a path to chassis ground for
the input. The pull-down resistor causes the voltage at an resistance temperature detector (RTD) Temperature mea-
input to drop to near 0V with nothing external to the module surement device, also known as platinum resistance ther-
connected to the input terminal. mometers (PRT).
pull-up resistor Part of an electronic module input circuit, resistive ladder network A form of analog multiplexing
a resistor that provides a path from a positive voltage source typically used with multiple function switches. Each switch
to the input. The pull-up resistor causes the voltage at an function causes a different value of resistance across the
input to rise to some value with nothing external to the corresponding switch terminals.
module connected to the input.
resistor An electrical component designed to have a spe-
pulse width modulation (PWM) A technique in which a cific value of resistance.
DC voltage source is switched off and on at a specific fre-
quency to reduce the DC voltage level to some average resistor block A high-power device that contains a stepped
value of voltage. The average voltage is regulated by con- resistor network used to control blower motor speed.
trolling the time that the voltage source is switched on
compared to the time that the voltage source is switched off. reverse-biased A diode that is blocking the flow of electric
The time for one complete on and off cycle divided by current.
the time that the voltage source is switched on is called the
duty cycle. PWM also refers to a digital communications rheostat A two-terminal variable resistor typically used to
technique. adjust current flow in a circuit.
pyrometer A gauge used to display diesel engine exhaust right-hand rule The method of determining the direction
temperature. of the arrows of the magnetic lines of force that surround a
current-carrying conductor.
random access memory (RAM) Temporary volatile mem-
ory, used as a scratch pad to hold digital information. ring gear A large diameter gear that is connected to the
engine crankshaft, and often a part of the flywheel, flex
readiness OBD indication of sufficient engine run time plate, or torque converter.
under required operating conditions for the ECM to have
completed all emissions system tests for that key cycle. ripple A low-level AC voltage that exists at the output of
an alternator. The AC ripple voltage rides on top of the DC
recombinant Refers to a type of sealed lead-acid battery voltage level.
where the oxygen and hydrogen gas formed during opera-
tion recombine to form water, which is drawn back into the rotor The rotating member of an alternator that supplies the
electrolyte solution. rotating magnetic field used to produce voltage in the stator
windings.
rectifier A device in an alternator that converts or rectifies
the negative half of a waveform into a positive waveform. routing The path followed by a wiring harness, such as
along the frame rail away from the exhaust.
reference ground Electronic module grounding scheme
where sensors are supplied with a dedicated return (ground) saturation The condition in which an increase in the input
circuit. The reference ground is connected to chassis ground signal produces no further change in the output of the de-
at one location within the electronic module. This reduces vice. A transistor that is saturated is used as a switch.
susceptibility to electromagnetic interference and provides
greater accuracy in sensor measurements. sealed beam A type of headlamp or other high-power light
that contains the lamp filaments, a reflector, and a lens in
reference voltage A positive voltage that is supplied to a one sealed assembly.
sensor or other device. The reference voltage is typically
regulated to some value such as +5V. selective catalytic reduction (SCR) Method of treating
exhaust outside of the combustion chamber (aftertreat-
relay An electromagnetic device with one or more sets of ment) to reduce oxides of nitrogen. Selective indicates
contacts that change position due to the magnetic attraction that only oxygen bonded with nitrogen is targeted. Am-
of an electromagnet. A small amount of current is capable of monia derived from a urea solution known as diesel ex-
controlling a large amount of current with a relay. haust fluid is dosed into the exhaust stream ahead of a
catalyst. The ammonia in the presence of the catalyst
reluctance The measure of a material’s opposition to causes the oxides of nitrogen to be transformed into ni-
magnetic lines of force. trogen and water.
reserve capacity A battery rating indicating for how many self-discharge The process of a battery discharging without
minutes new, fully charged batteries are capable of sup- any load connected across the terminals. Self-discharge
plying a continuous load of 25A while still maintaining a occurs more rapidly as temperature increases.
terminal voltage greater than 1.75V per cell (10.5V for a
12V battery) at a temperature of 808F. self-inductance A coil inducing a voltage within itself due
to the expanding or contracting magnetic field that sur-
residual magnetism The magnetism that remains in the rounds the coil when current flow through the coil changes.
rotor poles with no current flowing through the rotor field.
semiconductor A material that is neither a good conductor
nor a good insulator of electric current. In electronics terms,
semiconductor refers to doped silicon.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Glossary 523
sender A device that transforms liquid level, temperature, sinking A device that supplies a path for current flow to
or pressure into a corresponding resistance to be used by a ground. A low-side driver is said to sink current.
gauge.
slip ring In an alternator, the surface on the rotor on which
sending unit See sender. the brushes ride to supply paths for current flow through the
field windings. In steering wheels, slip rings are circular
sensor A device that converts some physical property into conductive paths that provide a means for making electric
an electrical signal. Sensors are also known as transducers. connections between stationary and rotating contacts.
separate stop/turn The stop lamps and turn signal lamps at smart actuator A remote device that contains a processor
the rear of a vehicle that do not share a common filament or and a communications interface. The smart actuator is able
lamp. Stop lamps must be red; turn signals can be red or to control some component with minimal instructions from
amber in color. another controlling element, such as an engine ECM.
series (connection) A means of connecting devices se- smart sensor A remote sensing device that contains a
quentially or one after the other. processor and a communications interface. Signal process-
ing and conditioning are contained within the smart sensor.
series circuit A circuit that has only one path through Complicated sensors such as NOX sensors are typically
which electric current can flow. Components that are con- smart sensors.
nected in series all have the same amount of current flowing
through them. smart switch Specialized switches containing a resistor
network used on the Freightliner M2 truck. Each switch is
series hybrid system A type of hybrid electric vehicle connected to the bulkhead module or expansion module via
system in which the vehicle is propelled only by electric three analog inputs. The resistance value of two identifica-
motors. The internal combustion engine in a series hybrid is tion resistors within each type of smart switch is unique to
used to generate voltage to power the electric motors. its function.
series-aiding Voltage sources connected so that the posi- Society of Automotive Engineers (SAE) A worldwide
tive terminal of one source is connected sequentially to the professional organization that develops standards used
negative terminal of another voltage source. throughout the automotive industry.
series-opposing Voltage sources connected so that the solenoid An electrically controlled device designed to
negative terminal of one source is connected sequentially to cause some remote mechanical movement. Solenoids may
the negative terminal of another voltage source. be used to control the flow of compressed air.
series-parallel circuit An electrical circuit composed of source (transistor) A terminal of a field effect transistor.
components such as resistors which have some elements in Current flows from the drain to the source terminals as
parallel with each other and other elements in series. controlled by the gate terminal.
series-wound A method connecting the armature windings source address SAE J1939 assigned numerical designation
of a motor and the field coils so that all are connected in of the device that has sent a J1939 message.
series.
sourcing A device that supplies current flow from a positive
shield A metal foil that is wrapped around conductors to voltage source. A high-side driver is said to source current.
reduce susceptibility to electromagnetic interference, spe-
cifically the effects of changing electric fields. A bare specific gravity The weight of the volume of any liquid
copper drain wire is often wrapped around the foil and is compared to an equal volume of pure water. Specific gravity
connected to ground through a capacitor (AC coupled) or has no units.
directly to ground (DC coupled) at one point in the system.
state of charge The indication of the percentage of chem-
short to ground An undesired condition in which an ical potential energy stored in a battery, compared to the
energized circuit has made contact with chassis ground. The maximum possible amount. A fully charged battery has a
short to ground has a very low resistance, causing a large 100 percent state of charge.
amount of current to flow.
stator The stationary windings that surround the rotor in an
shunt A specific value of resistance placed in a circuit for alternator. Voltage is induced in the conductive windings of
measuring current flow. The voltage dropped across the the stator.
shunt is used with Ohm’s law to determine the current
flowing through the shunt. stepper motor An electric motor that can be driven in
precise incremental steps or positions, used in modern truck
shunt-wound A method of connecting the armature wind- instrumentation to drive a gauge needle.
ings of a motor in parallel with the field coils.
stub A short section of twisted pair conductor that connects
signal conditioning Electronic module input circuitry that an electronic module to the backbone or main trunk of a
prepares the input signal for the next stage of the signal J1939 data link.
process. Signal conditioning includes capacitors for filtering
the signal and resistor networks to modify the voltage level suppression The use of a device in parallel with a coil (in-
at the input. ductor) to reduce the amplitude of the negative voltage spike
that occurs due to self-inductance when the magnetic field
silicon An element with four valence electrons. Pure silicon collapses when current flow through the coil is interrupted.
forms crystals, which are nonconductive. Silicon is doped
with impurities to form P-type and N-type materials to surface charge The condition in which gas bubbles on the
produce semiconductor devices. plates cause the battery to appear to be at a higher state of
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
524 Glossary
charge than actual. Surface charge is rapidly dissipated variable geometry turbocharger (VGT) Turbocharger
when a load is applied to the battery. with a variable aspect ratio. The position of the vanes is
controllable to modify the exhaust manifold pressure
suspect parameter number (SPN) SAE J1939 message (backpressure) and to control the air/fuel ratio.
packages which refer to a measureable factor such as SPN 110
engine coolant temperature. SPNs are also used in J1939 DTCs variable reluctance A type of sensor that uses a coil of
to define the system for which a failure has been detected. wire wrapped around a permanent magnet. A low-reluctance
timing disk or tone wheel is passed in front of the sensor,
tail lamp The red lamps at the rear of a vehicle. causing the magnetic lines of force created by the magnet to
be redirected into the low-reluctance disk.
telematics Convergence of telecommunications and in-
formatics. Informatics is the science of information. Tele- vehicle onboard radar (VORAD) Legacy forward radar
matics can be used to predict failure before the failure system for on-road trucks developed by Eaton, now incor-
occurs (prognostics). porated into Bendix advanced ABS systems.
terminals The conductive pins, sockets, and rings that virtual fusing A means of protecting a circuit by measuring
terminate the ends of wires. the amount of current conducted by an electronic switching
device such as an FET, and switching the device off if
terminating resistor A resistor that is placed across the current exceeds a predetermined value.
two conductors of a twisted pair communications network at
both extreme ends of the network, such as a J1939 data link. virtual sensor Calculated or modeled physical parameter
The terminating resistor helps reduce signal reflections that without the use of an actual sensor.
interfere with communications.
volatile memory Digital memory that is lost when power is
thermistor A variable-resistance sensor used to measure interrupted. RAM memory is volatile memory.
temperature.
volt The unit of measurement of electrical potential or
thermocouple A voltage-producing sensor that uses two voltage. One volt is the amount of electrical potential nec-
junctions of two dissimilar metals to measure temperature. essary to cause one ampere of current to flow through one
The voltage produced is proportional to the difference in ohm of resistance.
temperature between the two junctions.
voltage Electrical potential, also called electromotive force.
three-bar light Identification lamps contained in a single
strip. voltage drop The difference in electrical potential mea-
sured across a resistance. Analogous to pressure drop across
throw The number of positions that a switch can be moved a hydraulic circuit restriction.
and still complete a circuit; the number of different circuits
that each of the switch’s poles can control. voltage regulator A device used to maintain the output
voltage of an alternator to a defined value.
time-division multiplexing A multiplexing technique in
which the pair of wires is time-shared by each device. voltmeter A tool used to measure the difference in elec-
trical potential or voltage between two points. A voltmeter
tooth abutment A condition that occurs occasionally in is part of a digital multimeter.
cranking motors in which the teeth of the pinion gear do not
come into mesh with the teeth of the ring gear. watt A unit of measure of power. One horsepower is equal
to about 746 watts. In electric power, the product of voltage
torque-speed control (TSC) An SAE J1939 message and current.
(PGN 0) that indicates a desired engine torque or speed
reduction requested by some electronic module. Watt’s law A principle that states that electric power
measured in watts is equal to the voltage multiplied by the
total resistance This represents the equivalent resistance of current flowing through a device.
an entire electric circuit. The total voltage supply in a circuit
divided by the total resistance yields the total current flow in Wheatstone bridge An electrical circuit that can be used to
the circuit. determine an unknown resistance through the use of three
known-value resistors.
transfer function An equation that describes the relation-
ship between the physical parameter being measured by a windings Coiled conductors or wire typically used to de-
sensor and the output voltage of the sensor. scribe components within generators and electric motors.
transformer Electrical device consisting of two inductors, work Movement in the direction of an applied force.
which can increase or decrease a changing electrical volt-
age. The supply voltage is connected to the primary wind- wye (Y) A means of connecting the three phases of an al-
ings; the output is connected to the secondary windings. The ternator so that all three phases share a common connection.
ratio of the number of turns in the secondary windings to The shape of the windings is drawn such that the phases are
the number of turns in the primary windings determines the in the shape of the letter ‘‘Y.’’
voltage induced in the secondary windings.
xenon A noble gas used in arc lamps.
transistor Electronic device with three terminals, used as
an amplifier or a switch. zener diode A special diode designed to permit current
flow in the reverse-bias direction after the voltage dropped
tripped The term used to describe a circuit breaker that has across the diode is greater than the zener voltage.
opened due to excessive current flow.
zener voltage The level of reverse-biased voltage dropped
valence band The outermost shell of an atom, which de- across a zener diode that permits the diode to conduct in the
termines the electrical conductivity of the element. reverse-biased direction.
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Index
AAVA. See accessory air valve assembly low output voltage, 222–223 modulators, 486–488
absorbed glass mat (AGM) batteries, 160 maximum output, 221–222 operation, 488–489
AC. See alternating current output voltage test, 221 trailer interconnection cable, 297–298
A/C. See air conditioning output waveforms, 208 variable reluctance sensors in, 344
accelerator position sensor (APS), 444 pad-mount, 219 warning lamps, 491–494
accessory air valve assembly (AAVA), 431 positive output terminal, 213 wheel speed sensors, 494–496
accumulators, 69–70 ratings, 212–213 wiring, 500–501
active-high inputs, 366 reassembly, 232 anti-spin regulation (ASR), 489–490
active-low inputs, 367 relay terminal, 213 APS. See accelerator position sensor
actuators remote voltage sense terminal, 213–214 armatures, 101–102, 125, 239
simple, 196 CEMF and, 268–269
EUI, 449–453 terminals, 213–214 components, 241
rack, 447 testing, 224–232 in horns, 308
SAHR, 499 three-phase voltage and, 200–202 rotation, 244, 266
smart, 463 transformer rectifier, 216–217 service, 258–262
VGT, 462 unloaded charging voltage, 221–222 shorted-to-ground, 262
A/D converters. See analog to digital voltage regulation in, 209–212 single-loop, 266
voltage regulator terminal, 214 testing, 258
converters AM. See amplitude modulation windings, 241, 262
aftertreatment, 464–469 American Wire Gauge (AWG), 83 arsenic, 171–172
AGM batteries. See absorbed glass mat ammeters, 28–29, 45–46 ASR. See anti-spin regulation
for battery testing, 153–154 ATC. See automatic traction control
batteries clamp-on, 57 atmospheric pressure, 12, 26
air, electricity compared to, 12–15 d’Arsonval-type, 387 atoms, 15–16
air compressors, 13–14, 25 ammonia, 351, 469 attire, 1–3
air conditioning (A/C) amperes (amp), 18 automated manual transmission (AMT),
cold cranking, 144–145, 241
clutch coils, 176–177 cranking, 145 483–484
clutch control, 317–320 ampere-turns, 60 automatic traction control (ATC), 489–490
International Diamond Logic, 424–425 amp-hours, 161 automatic transmissions
thermistors, 341 amplifiers, 340
air core gauges, 391 bipolar transistors as, 180–181, 185–186 back-up lamps and, 295
air horns, 307, 309 differential, 341 ECU, 247, 478–483
air management unit (AMU), 430–431 amplitude modulation (AM), 345–346 AWG. See American Wire Gauge
air pressure measurement systems, 426 AMT. See automated manual transmission
Allison World Transmission, 478–483 AMU. See air management unit backbone, 374
alternating current (AC), 18–19, 193–194 analog back-feed, 292–293
alternators and, 176 digital versus, 351–354 back-up lamps, 295
converted to DC, 205–208 inputs, 366–369 barometric pressure. See atmospheric
producing, 196–200 multiplexing, 370–371
ripple, 149 outputs, 369 pressure
sinusoidal, 200 analog to digital (A/D) converters, base, 180
alternators, 191 batteries
AC and, 176 359–360, 416
brushless, 214–215 analogy, 16 AGM, 160
capacitors in, 73 AND gates, 356 arcing, 139
circuits, 213–214 anodes, 173–174 cables, 250
component testing, 226 antilock braking system (ABS), 484–501 cells, 132–133
disassembly, 224–232 chargers, 148–149
dual-voltage, 215–218 air, 485–497 charging, 130–131, 136
fundamentals, 192–213 drive axle, 489 charging current, 162
ground terminal, 213 ECU, 298, 301, 398, 485–489 chemical reactions in, 135–136
heat sinks, 207–208 hydraulic, 497–500 combined, 134–135
high output voltage, 223 conductance testing, 154–155
indicator lamp terminal, 213–214 connecting multiple, 138–139
525
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
526 Index
batteries (continued) blower motors, 314–317 case-based reasoning, 122
connections, 157–158 blown, 108–109 Caterpillar Regeneration System (CRS),
corrosion, 159 body controllers
DC and, 130 466–467
discharging, 130, 135–136, 161–163 headlamp, 421 cathodes, 173–174
disconnect switch, 224 inputs, 415–421 CBM. See condition-based maintenance
equalizers, 217–218 instrumentation and, 426 CCA. See cold cranking amperes
external components, 136–138 International, 410–412 CCOHS. See Canadian Centre
gelled cell, 160 outputs, 413–415
heaters, 143 overview, 411 for Occupational Health and Safety
HEV, 160–161 boron, 172–173 CCOT system. See cycling clutch orifice
high temperatures and, 143–144 Bourdon tube, 24–25
hold-downs, 158 brakes tube system
inspections, 159 bleeder, 329 CD. See candela
internal components, 131–136 compression, 329 cells, 132–133, 160
internal resistance, 139–142 differential, 490 CEMF. See counter-electromagnetic force
lead-acid, 5, 130–135 engine, 329–330 charge, 15. See also state of charge
lithium-ion, 6, 160–161 exhaust, 329–331
low temperatures and, 142–143 hydraulic booster, 330–333 opposite, 17
low water loss, 131, 151–152 brake systems. See also antilock braking system surface, 153
maintenance, 159 air, 180–181 charging, 130–131, 136
maintenance-free, 131, 154 energy conversion in, 76 circuit resistance, 219
overcharging, 147, 218 hydraulic power, 498–500 current, 162
parallel-connected, 138 warning lamps, 397–398 voltage, unloaded, 221–222
plates, 131–133 breakout box, 403–404, 438–439 charging systems
ratings, 144–146 breakout T, 104, 403, 438–439 components of, 192
recombinant, 159–160 brushes, 197 preliminary checks, 218–220
reserve capacity, 145–146 in DC motors, 237–238, 265 problems, 218–223
reverse polarity, 207–208 length of, 263 rapid assessment of, 263
safety, 5–6 servicing, 262 testing, 220–221
self-discharge, 144 testing, 232 visual inspection of, 218–219
series-connected, 138–139 brushless alternators, 214–215 voltage drop in, 219
state of charge, 141 bucking coils, 388–389 warning lamps, 398–399
system service, 157–159 bulkhead module (BHM), 429–430 chassis ground, 85–86
temperature and, 142–144 burns, 4 chassis module (CHM), 429–430
terminal markings, 138 bus topology, 374 chemical composition sensors, 350–351
terminals, 137–138 butt connectors, 87–88 chemical respirator, 8
terminal voltage of, 153 buzzers, 121 CHM. See chassis module
testers, 156 bytes, 355 chokes, 62–63
testing, 150–155 chuff test, 489
testing equipment, 153–154 CA. See cranking amperes circuit breakers, 105, 111–112, 121
undercharging, 218 cab harnesses. See wiring harnesses circuit protection devices (CPDs), 41, 105–115
very discharged, 148 cables, 83 application of, 114–115
voltage drop across terminals, 252 buzzers and, 121
voltage ratings, 144 battery, 250 HVAC, 315
VRLA, 159–160 jacketed, 87 layout, 115
water replenishment, 158–159 jumper, 155–157 replacing, 107
length, in trailer lighting, 299 types, 108–114
Battery Council International (BCI) group SAE J1939 specification, 373–374 circuits, 24. See also specific circuit types
number, 146 trailer ABS interconnection, 297–298 alternator, 213–214
cab over engine (COE) trucks, 6 analysis, 32–44
battery recharging, 146–149 camshaft position, 344–347 dry, 101
absorption stage, 163–164 CAN. See controller area network identification, 85
bulk stage, 163 Canadian Centre for Occupational Health and open, 115–117
charging current in, 162 parallel, 39–42
float stage, 164 Safety (CCOHS), 7 power window, 265
stages, 163–164 Canadian Motor Vehicle Safety Standards series, 37–39
series-parallel, 42–44, 363
BCI group number. See Battery Council (CMVSS), 274 transistor, 181
International group number candela (CD), 277 clamp-on current probe, 30–31, 57
capacitance, 72 clearance lamps, 274
Bendix R , 245 climate control panel, 317
bendix, 245 variable, 349–350 clipping, 86–87
BHM. See bulkhead module capacitors, 69–73 clocksprings, 308–309
bimetallic gauges, 384–387 carbon, 21, 161 closed loop control, 454–456
binary, 354 carbon piles clutches
bits, 355 coils, 176–177
bleeder brakes, 329 alternator maximum output and, 221–222 compressor, 319
blink codes, 494 for battery testing, 153–154 control, in air conditioning, 317–320
in charging system checks, 219–220
cranking system resistance and, 251
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Index 527
one-way, 245 crimping derate, 448
overrunning, 245 terminals, 91–92 desired output, 455
roller, 247 tools, 92 diagnosable switches, 417–420
sprag, 247 wire, 87–88 diagnostic connectors, 379
CMVSS. See Canadian Motor Vehicle Safety diagnostic flowchart, 117
CRS. See Caterpillar Regeneration System Diagnostic Optimized Connection (DOC),
Standards cruise control systems, 425–426
COE trucks. See cab over engine trucks current, 17 482–483
cold cranking amperes (CCA), 144–145, 241 diagnostic trouble code (DTC), 414
collector, 180 charging, 162
combination stop/turn lamps, 288, 292–295 direction of, 18 ABS ECU, 486
common, 102 draw, in starter motors, 241–243 confirmed, 470
common rail fuel systems, 457–461 excessive, 106–108, 117–123 electrical system troubleshooting and, 510
commutation, 240, 265–267 heat and, 105–106 HD-OBD, 470
commutators, 239 hold-in, 451 pending, 470
composite headlamps, 281–282 induced, 60 permanent, 470
compound-wound motors, 244 inrush, 106 previous MIL-on, 470
compression brakes, 329 instantaneous, 451 SAE J1939, 434–437
compressor clutch, 319 interrupted, through inductor, 63–65 Diamond Logic Builder, 433–434
condition-based maintenance (CBM), 502 leakage, 437 diatomic elements, 136
conductance testing, in batteries, 154–155 in magnetic fields, 238–239 dielectrics, 70
conductor loops, 198–199 magnetism and, 55–59 diesel engines
measuring, 36 diagnosis, 470–474
three-phase, 201 probes, 30–31 electronically controlled, 444–445
windings and, 202 ramped, 451 diesel exhaust. See exhaust
conductors, 19–20 rotor field, 211 diesel exhaust fluid (DEF)
magnetic fields around, 57–58 shunts, 30 battery disconnect switch and, 224
conduit, 86 sinking, 184 chemical composition sensors and, 351
confirmed DTC, 470 solving, 43 heaters, 469
connectors, 82, 88–93. See also specific sourcing, 184–185 SCR and, 467
surge, 280 urea in, 151
connector types current rating diesel oxidation catalyst (DOC), 465
hard-shell, 91 for diodes, 175 diesel particulate filter (DPF), 349, 464–465
locking devices, 93 lamp ratings and, 277 differential braking, 490
molded, 88–91 for switches, 100–101 differential pressure gauges, 26–27, 34–35
problems, 93–95 cycling clutch orifice tube (CCOT) system, digital, 351
sealed, 91 analog versus, 351–354
conspicuity, 274 424–425 electronics, 351–369
control circuits, 101, 103–104 inputs, 366–367
controller area network (CAN), 375–376, Darlington pair, 182 instrument panel, 394–396
d’Arsonval gauges, 387 numbering system, 354–355
507–509 data link, 371, 400 outputs, 369
conventional theory, 18 digital multimeter (DMM), 27–29, 45–46
copper, 16 International body controller, 411 breakout box with, 404
corrosion, 82 IPC and, 400 diode testing with, 176
SAE J1939, 410, 415, 421, 506–509 to find high resistance, 123–125
battery, 159 data mining, 502 peak hold and, 122
fretting, 94 daytime running lights (DRL), 286, 422 troubleshooting with, 437–439
terminal problems and, 94 DC. See direct current digital storage oscilloscopes (DSO), 472
coulombs, 17 DC motors digital volt-ohm meter (DVOM), 27
counter-electromagnetic force (CEMF), 63, brushed, 237–238, 265 diodes, 102, 173–179. See also light-emitting
CEMF and, 268
240, 267–269, 310–311, 452 compound-wound, 244 diodes
courtesy lamps, 301 improving, 241 alternators and, 191
covalent bonds, 170–172 interacting magnetic fields and, 58 applications for, 176–177
CPDs. See circuit protection devices permanent magnet, 265, 309–311 current rating, 175
cranking amperes (CA), 145 reversed rotation, 265 field, 211
cranking systems series-wound, 244 forward biased, 173–174
shunt-wound, 244 inverse voltage rating, 175
in cold weather, 253–254 simple, 239–240 negative, 207
diagnosing, 249–257 DC-to-DC converter, 218 as rectifiers, 205
diagnostic flowchart, 254 DEF. See diesel exhaust fluid reverse biased, 173–174
interlocks, 247–248 Delco Remy 22SI, 228–231 striped, 174
low temperatures and, 142–143 Delco Remy 28SI, 219 suppression, 320
magnetic switches in, 255–256 Delco Remy 37-MT, 258–261 testing, 176, 232
neutral start switches in, 256 Delco Remy 40SI, 205 trio, 211
problems, 254–257 delta, 202 turn-on voltage, 174
rapid assessment of, 263 Denoxtronic system, 468–469 zener, 177–179, 233
resistance, 249–252 Departronic system, 465
voltage drops in, 250
crank inhibit circuit, 247
crankshaft position, 344–345
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
528 Index
DIP switches, 392–394 electric fields, 68–69, 71 low temperatures and, 142
direct current (DC), 18–19 electricity viscosity, 85, 253
engine torque limiting (ETL), 489
AC converted to, 205–208 air compared to, 12–15 Environmental Protection Agency (EPA), 444
batteries and, 130 basics, 15–22 2007 standards, 464–466
discharging, 130, 135–136, 161–163 electric maps, 24 2010 standards, 467–469
disconnect switch, 224 electric motors. See DC motors EOBR. See electronic on-board recorder
DMM. See digital multimeter electric power, 53–54 EPA. See Environmental Protection Agency
DOC. See Diagnostic Optimized Connection; electric shock, 3–4 equivalent resistance, 42
electrolysis, 82 error, 456
diesel oxidation catalyst electrolytes, 131 measurement, 458–460
dome lamps, 301, 424 low temperatures and, 143 ESC. See electrical system controller
doping, 171 self-discharge and, 144 EST. See electronic service tool
dot matrix panel, 395 specific gravity of, 150–151 ETL. See engine torque limiting
double-pole double-throw (DPDT) electromagnetic interference (EMI), 372, 416 EUIs. See electronic unit injectors
electromagnets, 59–60, 199–200 EUP. See electronic unit pump
switches, 96 electromechanical gauges, 384–391 excitation voltage, 211
DPF. See diesel particulate filter electromotive force (emf), 17, 240. See also exhaust
drain, 183 aftertreatment, 464–469
drive-axle ABS event, 489 counter-electromagnetic force brakes, 329–331
drivers electronically controlled gauges, 391–394 emissions, 444–445
electronic brake force distribution (EBD), 499 emissions control, 461–470
high side, 184–185, 413–414 electronic clutch actuator (ECA), 503 in-cylinder emissions reduction, 461–464
low side, 184, 414–415 electronic control modules (ECM), 444 systems, 68
drives. See also fan drives exhaust gas recirculation (EGR), 348, 461–464
assembly, 262 analog inputs, 366–369 exterior lighting
mechanisms, 246 digital inputs, 366–367 components, 286–295
shift-lever-type, 246 engine fan drive, 323 International Diamond Logic, 421–424
starter motor, 245–247 fuel dosing system, 466 requirements, 274–277
DRL. See daytime running lights inputs, 361–362 eyewear, 2–3
DSO. See digital storage oscilloscopes outputs, 369
DTC. See diagnostic trouble code potentiometers and, 170 failure mode indicator (FMI), 434–435
dual-filament lamps, 279 warning lamps, 397 fan drives
dual-mode hybrid system, 504 electronic control unit (ECU), 444
duty cycle, 210–211 ABS, 298, 301, 398, 485–489 air engaged, 321
DVOM. See digital volt-ohm meter automatic transmission, 247, 478–483 engine, 319–323
electronic gauge cluster (EGC), 422 solenoids, 321–322
earth, 85 electronic on-board recorder (EOBR), 501 spring engaged, 321
EBD. See electronic brake force distribution electronics, 168 valves, 321–322
ECA. See electronic clutch actuator digital, 351–369 farads, 69, 72, 349
ECM. See electronic control modules electronic service tool (EST), 379, 401, fault code. See diagnostic trouble code
ECT. See engine coolant temperature Federal Motor Carrier Safety Administration
ECU. See electronic control unit 471–472
EEPROM. See electrically erasable, electronic unit injectors (EUIs), 448–453 (FMCSA), 274
Federal Motor Vehicle Safety Standards
programmable, read only memory camshaft actuated, 449
EGC. See electronic gauge cluster dual actuator, 452–453 (FMVSS), 247
EGR. See exhaust gas recirculation single actuator, 449–451 lighting system requirements, 274
electrical circuits electronic unit pump (EUP), 452–453 warning lamps, 398
electrons, 15 feedback, 292–293
capacitor, 70–72 displacing, 16–17 feedback control. See closed loop control
diagnostic flowchart for, 117 flow, 17–19 FETs. See field effect transistors
excessive current in, 106–108 free, 19 field coils, 240
fuses in, 107 valence, 170 open, 258
parallel, 40–42 emergency eye wash station, 3 pole shoes with, 243
series, 37–39 emf. See electromotive force shorted-to-ground, 258
series-parallel, 42–44 EMI. See electromagnetic interference testing, 258
simple, 36–37 emitter, 180 field effect transistors (FETs), 182–184, 359
electrically erasable, programmable, read energized, 102 fire extinguishers, 6–7
energy, 54 flashers, 286–287
only memory (EEPROM), 358–359 conversion losses, 76 flash memory, 359
electrical potential, 16 kinetic, 74–75 floating, 361
electrical system controller (ESC), 410 potential, 74–76 flow meters, 28–29
electrical systems engine brake systems, 329–330 FMCSA. See Federal Motor Carrier Safety
engine coolant temperature (ECT)
dual-voltage, 215–218 sensors, 341, 369 Administration
Freightliner multiplexed, 428–433 variable resistors and, 390 FMI. See failure mode indicator
International Diamond logic, 421–428 engine fan drive, 319–323 FMVSS. See Federal Motor Vehicle Safety
International multiplexed, 410–421 engine oil
rapid assessment of, 264 chemical composition sensors and, 351 Standards
troubleshooting, 504–510
electrical tools, 23–32
electric burns, 4
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Index 529
fog lamps, 424 Hall effect, 346–348, 484 hydraulic brake system booster, 330–333
footwear, 2 halogen, 277 hydraulic check valve, 174, 179
force, 54, 59–60 hydraulic circuits, 32–35
forward biased, 173–174 lamps, 282–283
freeze frame, 470 sealed-beam headlamps, 281 with differential pressure gauge, 34–35
Freightliner hardwire, 415 hydraulic accumulators in, 69–70
harmonic frequency, 351 parallel, 39–40
Century Class tractor, 274 harnesses, 82. See also wiring harnesses pressure drop in, 33
multiplexed electrical system, Hazard Communication Regulation, 7 restrictions in, 33–34
hazard lamps, 288, 290–291, 422–423 turbines in, 62
428–433 hazardous substances, 7 hydraulic compact unit (HCU), 498–499
frequency, 196 H-bridge, 463–464 hydraulic power brake (HPB) system, 498–500
HCU. See hybrid control unit; hydraulic hydraulic pumps, 87
fundamental, 351 hydrocarbons, 465
harmonic, 351 compact unit hydrogen, 135
fretting corrosion, 94 HD-OBD. See heavy-duty on-board Hydro-Max system, 330–332, 398
friction, 76 hydrometers, 150–153
fuel dosing systems, 465–466 diagnostics Hz. See hertz
fuel level headlamps, 280–286, 421–423
sending unit, 399 ICP. See injection control pressure
sensors, 386 body controllers, 421 ICU display. See instrument cluster unit
fuel systems, 445–461 composite, 281–282
common rail, 457–461 LED, 283–284 display
P-L-N, 445–448 lens, 281 identification lamps, 274
full-fielding, 211–212, 222–223 reflectors, 282 idle validation switch (IVS), 339
fundamental frequency, 351 sealed-beam, 281 IDM. See injector drive module
fuses, 105, 108–111 switches, 284–286 ignition coil, 67–68, 466
blade, 109–110 hearing protection, 3 ignition contacts, 68
blown, 108–109 heat impact wrench, 13–15
in electrical circuits, 107 current and, 105–106 impedance, 373
panel, 109–110 from energy conversion losses, 76 incandescent lamps, 277–280
SAE, 109–110 resistance and, 108
virtual, 114, 414 wire gauge and, 84 LED advantages over, 299–301
voltage rating of, 108–109 heated mirrors, 325–328 terminals, 279
wiring diagrams, 119 heat sinks, 207–208 indicator lamps, 213–214, 396–399, 403
fusible links, 105, 113 heavy-duty on-board diagnostics (HD-OBD), induced, 60–61, 193
inductors, 61–63, 450
gates, 183, 355–357 469–470 current interrupted through, 63–65
gauges Heisenberg uncertainty principle, 359 ramped current and, 451
henries, 61 suppression of, 66–68
air core, 391 hertz (Hz), 196 voltage amplitude in, 65–66
bimetallic, 384–387 HEUIs. See hydraulically actuated unit injection control pressure (ICP), 453–454
d’Arsonval, 387 injection pressure regulator (IPR), 453, 455
differential pressure, 26–27, 34–35 injectors injection pumps
electronically controlled, 391–394 HEV. See hybrid electric vehicles port-helix, 446–447
magnetic, 387 high intensity discharge (HID) lamps, 283 rotary distributor, 447–448
mechanical, 384 high side drivers, 184–185, 413–414 injector drive module (IDM), 454
pressure, 24–26 hold-in coils, 269 injectors
sine-cosine, 392 hoods, tilting, 6 mechanical unit, 448
stepper-motor-driven, 401–403 horns, 307–309 piezo, 460–461
strain, 348–349 solenoids, 450
three-coil, 388–389 circuits, 310 inputs, 359, 444
two-coil, 389–391 International body controllers and, 412–413 active-high, 366
gear-reduction starter motor, 248–249 horsepower, 54, 75 active-low, 367
GFCI. See ground fault circuit interrupter HPB system. See hydraulic power brake system adding external devices to, 362–366
ghost voltage, 437–439 HVAC systems, 131, 314–323 AMT, 483–484
gloves, 2 assemblies, 316 analog, 366–369
glow plugs, 142 blower motors, 314–317 body controller, 415–421
GPE. See gravitational potential energy CPDs, 315 digital, 366–367
gravitational potential energy (GPE), mode control, 323 ECM, 361–362
sleeper cab, 316 electronic module, 366–367
75–76 temperature control, 323 hardwired, 415
ground, 85–86 wire-wound resistors in, 169 microprocessor, 359–361
hybrid control unit (HCU), 403 pulled-down, 365–367
chassis, 85–86 hybrid electric vehicles (HEV), 160–161 pulled-up, 368
reference, 415–417 hybrid systems, 502–504 SAE J1939 data link, 421
short circuits to, 116 dual-mode, 504 types, 369
short to, 107–108 electric shocks from, 4 windshield wiper, 427
terminal, 4, 149, 213 parallel, 503
ground fault circuit interrupter (GFCI), 4 series, 503
growler, 258 hydraulically actuated unit injectors (HEUIs),
453–458
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
530 Index
in-range failure, 458 courtesy, 301 magnetic fields, 54–55
inrush current, 106 dome, 301, 424 canceling, 58
instrumentation dual-filament, 279, 291–292 collapsing, 65
engine warning, 396–397 around conductors, 57–58
body controllers and, 426 filaments, 289–290 currents in, 238–239
conventional, 384–399 fog, 424 interacting, 58–59, 238
multiplexed, 399–403 halogen, 282–283 in looped wires, 59
SAE J1587/J1708, 399–401 hazard, 288, 290–291, 422–423 rotating, 197–198
SAE J1939, 401–403 HID, 283 in rotors, 204
instrument cluster unit (ICU) display, 429, identification, 274 self-inductance caused by, 63
incandescent, 277–280 strength, 60
431–432 indicator, 213–214, 396–399, 403
instrument panel license, 277 magnetic lines of force, 54–55
marker, 274 cutting, 60–61, 192
digital, 394–396 miniature, 278 direction of, 238
illumination, 210, 302 panel illumination, 302–302
instrument panel cluster (IPC), 383, 400 parking, 277 magnetic poles, 55–56
instrument voltage regulator (IVR), ratings, 277–279 magnetic switches, 105, 255–256
running, 421–422 magnetism, 54–61, 238–239
385–387 separate stop/turn, 288
insulation, 83 short circuits in, 293 current and, 55–59
stop, 287–288, 423 residual, 211
heat-shrink, 87–88 tail, 274 right-hand rule of, 56
SAE J560 standards, 296 three function, 289–290 voltage from, 192–193
thermocouple, 343 LAN. See local area network magnets, permanent, 265, 309–311
wire, 84–85 latched relays, 333–334 malfunction indicator lamp (MIL),
insulators, 22 latching, 96
intake air heaters, 142 LCD. See liquid crystal display 469–470
integrated circuits, 357 lead, 135–136 manifold absolute pressure (MAP),
interior lighting, 301–302, 421–424 lead dioxide, 131, 135
interlocks, 247–248, 414–415 leakage current, 437 26, 463
internal resistance, 46 learn cycle, 463 manufacturer service information,
battery, 139–142 LEDs. See light-emitting diodes
in very discharged batteries, 148 Lenz’s law, 65 505–506
International Diamond Logic, 421–428 license lamps, 277 MAP. See manifold absolute pressure
International Organization for Standardization light bulb filament, 21 marker lamps, 274
light-emitting diodes (LEDs), 177 material safety data sheet (MSDS), 7
(ISO), 83, 396 advantages of, 299–301 mean spherical candela (MSCD), 277
ions, 16 construction, 301 measured output, 455
IPC. See instrument panel cluster disadvantages of, 301 measurement error, 458–460
IPR. See injection pressure regulator displays, 394–395 mechanical gauges, 384
air compressors, 25 headlamps, 283–284 mechanical unit injectors (MUIs), 448
ISO. See International Organization for in heated mirrors, 328 megahertz (MHz), 196
lighting technology, 298–301 memory, 358–359
Standardization lighting systems, 273–277. See also mercury, 12–13
IVR. See instrument voltage regulator message identification (MID), 372, 437
IVS. See idle validation switch exterior lighting; interior lighting; metric prefixes, 44
trailer lighting MHz. See megahertz
Jake Brake, 329 LIN. See local interconnect network microprocessors, 357–361
Jacobs Vehicle Systems, 329 linear Hall effect sensors, 484 microswitches, 420
jewelry, 2 linear power module (LPM), 317, 319 MID. See message identification
JFETs. See junction field effect transistors liquid crystal display (LCD), 394–396 Midtronics EXP battery tester, 156–157
joules, 54, 74 lithium manganese oxide, 161 MIL. See malfunction indicator lamp
jumper cables, 155–157 load, 98 milling, 247
jump-starting, 155–157 load dump, 223 mirrors, 325–328
junction field effect transistors (JFETs), LOADpro, 439 modular trailer wiring, 298
local area network (LAN), 507 modulators, 486–488
183–184 local interconnect network (LIN), momentary contact, 96
junctions, 172–173 377–378, 465 MOSFET, 184, 287, 413
lockout/tag-out safety procedure, 6 motorized mirrors, 325–327
key storage, 6 logic, 355 motors. See also DC motors
kinetic energy, 74–75 logic gates, 355–357
Kirchhoff’s current law, 41, 43, 46–47 lookup tables, 456 blower, 314–317
Kirchhoff’s voltage law, 38–39, 43, looped wire, 59 stepper, 401–403
low side drivers, 184, 414–415 windshield wiper, 309–311
46–47, 175 LPM. See linear power module MSCD. See mean spherical candela
MSDS. See material safety data sheet
lamps. See also headlamps; specific lamp MUIs. See mechanical unit injectors
types multifunction switches, 321, 432
multiplexing, 370–372
back-up, 295 analog, 370–371
bases, 279 Freightliner electrical system, 428–433
brake system warning, 397–398
clearance, 274
combination stop/turn, 288, 292–295
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Index 531
instrumentation, 399–403 body controller, 413–415 power distribution modules (PDMs), 109, 114
International electrical system, 410–421 desired, 455 power electronics carrier (PEC), 503
SmartPlex, 432–433 digital, 369 power line carrier (PLC) signal, 495
time-division, 371–372 ECM, 369 power net distribution box (PNDB), 111
troubleshooting, 378–379, 433–329 measured, 455 power steering fluid flow, 330
microprocessor, 359–361 power take off (PTO), 87, 415, 504
NCMH. See normal cubic meters per hour overcharging, 147, 218 power windows, 323–324
needle control valve (NCV), 452 overcrank protection (OCP) switch, 248
negative temperature coefficient (NTC), 170, overrunning clutch, 245 circuit, 265
oxidation, 94 switches, 324–325
234, 340–341 oxides of nitrogen (NOx), 351, 444 preliminary inspections, 118
negative voltage spike, 66–67 regulation, 461 pressure drops, 33, 35
neutral start back-up (NSBU) switch, 481 SCR and, 467–468 pressure gauges, 24–26
neutral start switches, 256 oxygen, 136, 351 pressure relief valve, 178
neutrons, 15 pressure sensors, 348–350
newtons, 54 panel illumination lamps, 302–302 air, 365
no-load voltage, 141 parallel, 28 piezoelectric, 349–350
nonlinear, 55 potentiometric, 348
nonvolatile memory, 358 circuits, 39–42 strain gauge, 348–349
NOP. See nozzle opening pressure hybrid systems, 503 transfer functions for, 365
NOR gates, 357 resistors, 44–45 variable capacitance, 349–350
normal cubic meters per hour (NCMH), 20 parameter group number (PGN), 376 previous MIL-on DTC, 470
normal state, 96–97 parameter identifier (PID), 372, 437 programmable parameters, 400
NOT gates, 357 parasitic loads, 222 property sensors, 350–351
NOx. See oxides of nitrogen key-off, 223–224 proportional solenoids, 447
nozzle opening pressure (NOP), 445 testing, 225 protons, 15
nozzle valve motion sensor (NVMS), 448 parking lamps, 277 PRT. See platinum resistance thermometers
NSBU switch. See neutral start back-up particulate matter (PM), 444, 461 PTC. See positive temperature coefficient
pattern failures, 122 PTO. See power take off
switch PDCs. See power distribution centers P-type materials, 172–173, 179–180
NTC. See negative temperature coefficient PDMs. See power distribution modules pull-down resistors, 365
N-type materials, 171–172, 179–180 peak hold, 122 pull-gauges, 94
NVMS. See nozzle valve motion sensor PEC. See power electronics carrier pull-in coils, 269–270
pending DTC, 470 pull-up resistors, 362–364
OBD. See on-board diagnostics permanent DTC, 470 pulse width modulation (PWM), 210–211, 233
OC. See occurrence count permanent magnets, 265, 309–311 in DRL, 286
Occupational Safety and Health PGN, See parameter group number in instrument panel illumination, 302
phase, 201 variable capacitance pressure sensors
Administration (OSHA), 1 PID. See parameter identifier
occurrence count (OC), 435 piezoelectric, 349–350 and, 349
OCP switch. See overcrank protection switch piezo injectors, 460–461 pump-line-nozzle (P-L-N) fuel systems,
OCV. See open-circuit voltage pinion gears, 245
OEM. See original equipment manufacturer clearance, 263 445–448
ohmmeters, 31–32, 122 milling, 247 PWM. See pulse width modulation
ohms, 20 plates, 131–133 pyrometers, 342
Ohm’s law, 22–23 platinum resistance thermometers
quantum physics, 16
Kirchhoff’s laws and, 47 (PRT), 342 quantum tunneling, 359
series circuits and, 39 PLC signal. See power line carrier signal quartz sensing element, 350
wire resistance and, 84 P-L-N fuel systems. See pump-line-nozzle
on-board diagnostics (OBD), 414 rack actuator, 447
one-way clutch, 245 fuel systems radar, 491
open-circuit voltage (OCV), 141 PM. See particulate matter radians, 75
open loop control, 456–457 poles, 95–96 random access memory (RAM), 358
optical refractometer, 151–152 pole shoes, 240 rate of change, 66
OR gates, 356–357 RDU. See remote diagnostic unit
ORH. See out of range high with field coils, 243 readiness, 470
original equipment manufacturer (OEM), multiple, 241 reciprocals, 44
polymers, 113–114 recombinant, 159–160
4, 122 port-helix injection pumps, 446–447 rectifiers, 205
ORL. See out of range low position sensors, 343–346
oscilloscopes, 67, 472–474 positive engagement, 246 assemblies, 208
positive temperature coefficient (PTC), 105, bridge, 206
troubleshooting with, 195 three-phase, 207
voltage waveforms and, 194–195 113–114, 170 reducers, 20
OSHA. See Occupational Safety and Health potential, 16 reference ground, 415–417
potential energy, 74–76 reference voltage, 349
Administration potentiometers, 170, 172, 343, 348 refrigerants, 425
out of range high (ORH), 435–436 power, 75 relay coil suppression, 102
out of range low (ORL), 435–436 power distribution centers (PDCs), 114
outputs, 359, 444
analog, 369
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
532 Index
relays, 67, 101–105 ring gears, 245, 247 SENT. See single edge nibble transmission
bipolar transistors as, 182, 186–187 ripple, 149, 206 separate stop/turn lamps, 288
breakout T, 104 RMS voltage. See root mean square voltage separators, 132
components, 101 roll stability control (RSC), 490 serial data communications, 371–372
control circuits, 103–104 root mean square (RMS) voltage, 232–233 serial processing, 360
energized, 102 rotary distributor injection pumps, 447–448 series, 29
fail-safe, 433 rotational speed sensors, 343–346 series-aiding, 133
hold-in voltage and, 125 rotors, 199–200 series circuits, 37–39
larger, 104–105 series hybrid systems, 503
latched, 333–334 components, 203 series-opposing, 134
operation, 101–102 details, 202–204 series-parallel circuits, 42–44, 363
panel, 110 field coil, 209 series-wound motors, 244
problems, 102–104 field current, 211 service information system (SIS), 505
pull-in voltage and, 125 full-fielding of, 222 ServiceLink, 433
with resistor suppression, 104 magnetic fields in, 204 shielding, 373–374
single-pole double-throw, 102 testing, 226 shift selectors, 480
terminals, 101–102, 213 routing, 86–87, 113 short circuits, 115–116
troubleshooting, 103–104 RSC. See roll stability control
RTD. See resistance temperature detectors diagnosable switches and, 420
relay valves, 180–181 running lamps, 421–422 to ground, 116
reluctance, 59, 199, 344 intermittent, 120–122
SA. See source address in lamps, 293
variable, 343–346, 496 SAE. See Society of Automotive Engineers wire-to-wire, 116
remote diagnostic unit (RDU), 494–495 safety short to ground, 107–108
residual magnetism, 211 armature, 262
resistance, 20–21. See also internal attire, 1–3 field coil, 258
battery, 5–6 shunts, 30
resistance; total resistance battery recharging, 148–149 shunt-wound motors, 244
charging circuit, 219 electrical, 3–6 SID. See subsystem identification number
in cranking systems, 249–252 glasses, 2–3 siemens, 155
equivalent, 42 jump-starting, 155 signal conditioning, 361
heat and, 108 lithium-ion battery, 160–161 silicon, 170
high, 123–125 personal, 6 covalent bonds, 172
increasing, 37 wall socket, 4–5 doped, 171
measuring, 31–32 SAHR actuators. See spring-applied silicone, 170
Ohm’s law and, 22–23 single edge nibble transmission (SENT), 378
switch contact, 97–98 hydraulically released actuators single-pole double-throw (SPDT) relays, 102
temperature versus, 341–342 sampling rate, 353 single-pole double-throw (SPDT) switches,
variable, 364 saturation point, 182
windings, 226 SCFM. See standard cubic feet per minute 96, 284–286
wire, 21, 83–84 SCR. See selective catalytic reduction single-pole single-throw (SPST) switches,
resistance temperature detectors (RTDs), 342 sealed-beam headlamps, 281
resistive ladder networks, 431 selective catalytic reduction (SCR), 467–468 95–96
resistor blocks, 314, 317 self-diagnostics, 433–434 sinking current, 184
resistors, 20–21, 168–170 self-discharge, 144 SIS. See service information system
capacitors discharging through, 72 self-inductance, 63 sleeper cab
color code, 168–169 semiconductors, 170–173, 181
fixed-value, 168–169 senders, 384 HVAC systems, 316
infinitely variable, 170 sending unit, 384, 386 lighting, 302
instantaneous current and, 451 sensors, 340–351. See also specific sensor slip rings, 197, 308
parallel, 44–45 smart actuators, 463
pull-down, 365 types SmartPlex multiplexing, 432–433
pull-up, 362–364 ammonia, 469 smart sensors, 468
in series circuits, 37–38 chemical composition, 350–351 smart switches, 429–430
in simple electrical circuit, 36 ECT, 341, 369 smoking, 6
stepped, 169 fuel level, 386 Society of Automotive Engineers (SAE), 85
suppression, 104 Hall effect, 346–348 circuit breakers, 112
terminating, 374–375 linear Hall effect, 484 fuses, 109–110
variable, 169–171, 363, 390 position, 343–346 J560 standards, 296
wire-wound, 169 property, 350–351 J1587 standards, 372, 399–401
restrictions rotational speed, 343–346 J1708 standards, 372, 399–401
in hydraulic circuits, 33–34 smart, 468 J1939 standards, 372–377, 401–403
in parallel hydraulic circuits, 40 soot, 351
pressure drops across, 35 speed, 480 cruise control systems and, 425–426
reverse biased, 173–174 temperature, 340–343 data links, 410, 415, 421, 506–509
rheostats, 172, 302, 343 variable reluctance, 343–346 DTC, 434–437
right-hand rule, 56 variable resistance, 364 FMI, 435
Right-to-Know Law, 7 virtual, 463 SPN, 434
wheel-speed, 345, 485–488, 494–496 J2394 standards, 298
soldering, 89–90
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
Index 533
solenoids, 245–246 subsystem identification number (SID), 437 low, 142–143
AMU, 430–431 sulfate, 135–136, 141–142 resistance versus, 341–342
fan drive, 321–322 sulfur contamination, 469 self-discharge versus, 144
in gear-reduction starter motors, 249 sulfuric acid, 5 sensors, 340–343
high side drivers and, 185 voltage regulators and, 233–234
injector, 450 electrolytes and, 131 terminals, 82, 88–93. See also specific
proportional, 447 neutralizing, 130
servicing, 262–263 overcharging and, 147 terminal types
windings, 269–270 reactions, 135 common, 102
specific gravity of, 150 corrosion, 94
soot sensors, 351 suppression, 66–68 crimping, 91–92
source, 183 diodes, 320 extracting, 93
source address (SA), 376, 435 relay coil, 102 locking devices, 93
sourcing current, 184–185 resistor, 104 problems, 93–95
spark plugs, 68 surface charge, 153 pull-to-seat, 93
SPDT relays. See single-pole double-throw surge current, 280 push out, 94
suspect parameter number (SPN), 376, 434 relay, 101–102, 213
relays SV. See spill valve solid barrel, 92
SPDT switches. See single-pole double-throw switches, 95–101. See also specific switch voltage, 153
terminating resistors, 374–375
switches types test lights, 123
specific gravity, 150–151 back-up lamp, 295 thermal limiters, 314–315, 317
speedometers, 391 battery disconnect, 224 thermal protection, 248
bipolar transistors as, 182, 186–187 thermistors, 340–342
mechanical, 384 contacts, 97–98 thermocouples, 342–343
programming, 392–394 current rating for, 100–101 three-bar light, 274
spill valve (SV), 452 defective, 124–125 three-coil gauges, 388–389
SPN. See suspect parameter number diagnosable, 417–420 throws, 95–96
spring-applied hydraulically released flow, 330–333 time-division multiplexing, 371–372
Hall effect, 346 timing circuits, 73
(SAHR) actuators, 499 headlamp, 284–286 tooth abutment, 246–247
spring potential energy, 76 ignition, 96–97 top dead center (TDC), 243
SPST switches. See single-pole single-throw knife, 95 torque, 75
latching, 96 torque speed control (TSC), 489
switches logic gates and, 356–357 total resistance
stability control, 490–491 magnetic, 105, 255–256 with multiple resistors, 44–45
standard cubic feet per minute (SCFM), 20 momentary contact, 96 in parallel circuits, 41–42
starter motors, 237, 241–248 multifunction, 321, 432 in series circuits, 38–39
neutral start, 256 tracers, 85
battery internal resistance and, 142 normally closed, 97 trailer ABS interconnection cables, 297–298
cranking system interlocks, 247–248 normally open, 97 trailer connections, 296–297
current draw, 241–243 power window, 324–325 cord connectors, 298
cutaway view of, 242 pressure, 317–319 socket, 298
disassembly, 257–263 problems, 97–101 trailer lighting, 295–298
drive assembly, 262 replacement, 100–101 cable length, 299
drives, 245–247 rotary, 371 wiring, 297
fundamentals, 243–244 series-parallel, 216 transfer function, 365–366
gear-reduction, 248–249 smart, 429–430 transformer rectifier alternators, 216–217
low temperatures and, 142 stop lamp, 287–288 transformers, 67–68
no-load bench-test, 257 troubleshooting, 98–100 transistors, 179–185
positive engagement, 246 types, 95–97 bipolar, 179–182, 185–187
power and, 75 voltage drops across, 98–99 circuits, 181
reassembly, 263 windshield wiper, 312–313 field effect, 182–184, 359
solenoid windings, 269–270 switch packs, 420–421 junction field effect, 183–184
testing, 257–263 NPN, 180–181
thermal protection, 248 tachometers, 391 PNP, 180
state of charge, 141 DIP switches for, 394 saturated, 186
temperature-corrected specific gravity and, programming, 392–394 saturation point, 182, 187
stepper-motor-driven, 402 voltage drop across, 186
151 transmissions, 477–484. See also automatic
terminal voltage and, 153 tail lamps, 274, 291–292
stators, 199 TDC. See top dead center transmissions
delta-connected, 202 telematics, 502 tripped, 111, 113
details, 204–205 temperature truth tables, 356–357, 427
testing, 227 TSC. See torque speed control
three-phase, 207 batteries and, 142–144 tungsten, 21, 170, 278
winding arrangements, 203 control, 323 turbines, 62
Y-connected, 202–203 corrected specific gravity, 151
stepper motors, 401–403 high, 143–144
stop lamps, 287–288, 423
strain gauges, 348–349
strain relief, 87
stubs, 374
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
534 Index
turn signals, 288, 422–423 sources, 133–134 windings, 202
two-coil gauges, 389–391 spike, negative, 66–67 armature, 241, 262
terminal, 153 arrangements, 203
UART. See universal asynchronous receiver/ tests, output, 221 delta-stator, 206
transmitter three-phase, 200–202 resistance, 226
turn-on, 174 shorted, 227
universal asynchronous receiver/transmitter unloaded charging, 221–222 solenoid, 269–270
(UART), 377 wall sockets, 41 three-phase, 204
waveforms, 194–196, 198
universal joints, 85 zener, 177, 233 windshield wipers, 169–170, 309–314
urea, 151 voltage drops, 36–37 inputs, 427
across battery terminals, 252 intermittent, 314
vacuums, 25–26 in charging systems, 219 International Diamond Logic, 426–428
vacuum tubes, 179 in cranking systems, 250 motors, 309–311
valence bands, 19 across switches, 98–99 switches, 312–313
valve-regulated lead-acid (VRLA) batteries, across transistors, 186
voltage rating wire
159–160 of batteries, 144 color-coded, 85
variable geometry turbocharger (VGT), of fuses, 108–109 crimping, 87–88
inverse, of diodes, 175 details, 83–85
329, 462 lamp ratings and, 277 diameter, 83
variable reluctance sensors, 343–346, 496 voltage regulators, 209–211. See also gauge, 84
variable turbine geometry (VTG), 462 insulation, 84–85
vehicle interface module (VIM), 478 instrument voltage regulator jumper, 104
vehicle onboard radar (VORAD), electronic, 211–212, 233–234 looped, 59
temperature and, 233–234 replacement, 106
491–492 terminal, 214 resistance, 21, 83–84
vehicle personality module (VPM), 454 testing, 232 stranded, 83
vehicle speed sensor (VSS), 393 voltmeters, 27–28, 45
VGT. See variable geometry turbocharger for battery testing, 153–154 wiring, 82–95
VIM. See vehicle interface module in charging system testing, 220–221 ABS, 500–501
virtual fusing, 114, 414 current probes, 31 diagrams, 118–119
virtual sensor, 463 volts, 17 excessive current in, 117–123
viscosity, engine oil, 85, 253 VORAD. See vehicle onboard radar modular trailer, 298
visual inspections, in wiring troubleshooting, VPM. See vehicle personality module trailer lighting, 297
VRLA batteries. See valve-regulated troubleshooting, 115–125
118
volatile memory, 358 lead-acid batteries wiring harnesses, 82
voltage, 17 VSS. See vehicle speed sensor attachments, 87
installing, 87
alternator high output, 223 wall sockets protection, 86–87
alternator low output, 222–223 polarity, 195–196 repair, 87–88
amplitude, in inductors, 65–66 safety, 4–5 routing, 86–87
excitation, 211 voltage, 41 sealed, 300
ghost, 437–439
hold-in, 125 warning lamps, 396–399, 403, 491–494 work, 53–54, 74
induced, 60–61, 193 water in fuel (WIF) sensors, 351 Workplace Hazardous Materials Information
from magnetism, 192–193 water replenishment, in batteries, 158–159
measuring, 24–28 watts, 54 System (WHMIS), 7
no-load, 141 Watt’s law, 54, 105 World Transmission Electronic Controls
Ohm’s law and, 22–23 Wheatstone bridge, 348–349
open-circuit, 141 wheel-bearing adjustment, 345 (WTEC), 478
polarity, 196 wheel-speed sensors, 345, 485–488, wye (Y), 202
pull-in, 125
reference, 349 494–496 xenon, 283
regulation, 209–212 WHMIS. See Workplace Hazardous
reverse-polarity, 65–66 Y. See wye
RMS, 232–233 Materials Information System
self-induced, 63 WIF sensors. See water in fuel sensors zener diodes, 177–179, 233
sense terminal, 213–214 zener voltage, 177, 233
solving, 43 zero-volt reference (ZVR), 415
Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.
The words you are searching are inside this book. To get more targeted content, please make full-text search by clicking here.
MODERN DIESEL TECHNOLOGY ELECTRICITY ELECTRONICS
Discover the best professional documents and content resources in AnyFlip Document Base.
Search
MODERN DIESEL TECHNOLOGY ELECTRICITY ELECTRONICS
- 1 - 50
- 51 - 100
- 101 - 150
- 151 - 200
- 201 - 250
- 251 - 300
- 301 - 350
- 351 - 400
- 401 - 450
- 451 - 500
- 501 - 546
Pages: