E Textbook Power Train & Chassis M2

5. SUPPLEMENTAL RESTRAINT SYSTEM

2. SYSTEM OPERATION
1. Dual Stage Airbags/ Knee Airbag/ Seat Belt Pre-tentioner
SRS-ECU uses data of the front impact sensor (in engine compartment) and G-sensor (in SRS-ECU)
to calculate collision severity during frontal collision. SRS-ECU judges necessity of 2nd deployment
of the dual stage airbag based on the calculated collision severity. In addition, the SRS-ECU also
judges the operation of knee airbag and seat belt pre-tensioner after calculating collision severity.

Component Light impact crash Heavy impact crash

Driver’s airbag Only 1st stage 1st and 2nd stage at
module the same time

Front passenger’s Only 1st stage 1st and 2nd stage at
airbag module the same time

Fig. 5-4

2. Side and Curtain Airbags
SRS-ECU uses data of the side impact sensor and G-sensor (in SRS-ECU) to calculate collision se-
verity, during side collision. SRS-ECU judges necessity of side-airbag and curtain airbag based on
the calculated collision severity.

Pub. No. PTAE1310 Fig. 5-5
5-4

5. SUPPLEMENTAL RESTRAINT SYSTEM

3. SYSTEM CONSTRUCTION

1. Driver’s Airbag Module

To deploy the air bag in two stages, the inflator of driver’s airbag
module is equipped with two squib connectors.

Fig. 5-6 2. Front passenger’s Airbag Module
Fig. 5-7 The front passenger’s airbag module consists of an air-
Fig. 5-8 bag, and their fasteners. The airbag is made from nylon
and inflates by the gas from the inflator. As a passenger
Fig. 5-9 is being pressed to the airbag, it deflates, discharging
Fig. 5-10 gas from two vents at the side of the airbag to reduce
the shock from the impact. The inflator has two squib
connectors to deploy the airbag in two stages.

3. Knee Airbag Module
The knee airbag module consists of a cover, an airbag,
an inflator, and the fixing gear relating to those parts,
and is installed under the steering column. Like the driv-
er’s and front passenger’s airbags, the knee airbag is
inflated upon a frontal collision for better protection of
the driver.

4. Side-Airbag Module
The side-airbag module consists of an airbag, airbag cover, inflator
and their fasteners. The modules are installed in the outer side sup-
ports of the driver’s and front passenger’s seatbacks. The side-
airbags help protect the occupants regardless of the seat position
and seatback angle.
The airbags are compactly folded and stored under the cover. On
the side of the airbag, there are holes through which gas is partially
released to ease shock to the occupant when the air bag is de-
ployed.

5. Curtain Airbag Module
The curtain airbag module consists of an airbag, an in-
flator, and the fixing gear relating to those parts, and is
installed in the roof side sections (from the driver’s and
the passenger’s front pillars to the rear pillars).

5 - 5 Pub. No. PTAE1310

5. SUPPLEMENTAL RESTRAINT SYSTEM

<Inflator>
The inflator is incorporated into the every airbag module. When the airbag module is deployed, the
SRS-ECU sends the ignition signal to the inflator, and it generates the gas to deploy the airbag.
The inflator consists of squib, igniter, gas generating agent, diffuser screen, etc. contained in an alu-
minum container. The bottom of the inflator is provided with an electrical connection to which an igni-
tion current is supplied. When current is supplied to the squib, a small amount of explosive in the
squib is burnt causing the igniter to burn, and the resultant heat burns the gas generating agents.
Combustion of the gas generating agents rapidly produces nitrogen gas which is forced through the
diffuser screen into the airbag. The diffuser screen serves as a filter to remove cinders and also helps
cool down the gas temperature and reduce the gas generation noise.

Gas generation agent

Fig. 5-11

6. Clock Spring
The clock spring is provided between the steering wheel (airbag module) and the column switch body
(steering column), and it provides harness connections between the airbag module and the SRS-
ECU.
The clock spring consists of a neutral position indication mechanism, flat cable, upper case, lower
case, rotor, etc. The flat cable loosely wound like a coil held in the upper and lower cases with one of
its ends mounted to the rotor and the other end mounted to the upper case. The upper and lower
cases are mounted to the steering column. The rotor is coupled with the steering shaft. Rotation of
the steering wheel (steering shaft) causes the rotor to rotate. Accordingly, the flat cable is wound
around the rotor or loosened, and operates with the rotor as the steering wheel is turned.

SRS-ECU

Pub. No. PTAE1310 Fig. 5-12
5-6

5. SUPPLEMENTAL RESTRAINT SYSTEM

Fig. 5-13 7. Front Impact Sensor
◇ The front impact sensor is installed on the head-

lamp support panel upper in the engine room, and
the analogue G-sensor is housed in the front impact
sensor.
◇ The front impact sensor transmits the coded accel-

eration data to SRS-ECU. Based on the data, SRS-
ECU determines the deployment stage of the front
airbag, then energizes appropriate squib.
◇ SRS-ECU performs the diagnosis of the front im-

pact sensor internal components. If a malfunction
occurs, it sets the diagnosis code.

Fig. 5-14 8. Side Impact Sensor
◇ The side impact sensors are installed to the lower

part of the centre pillars on both sides and the ana-
logue G-sensor is housed in the side impact sensor.
◇ The side impact sensor transmits the coded accel-

eration data to SRS-ECU. Based on the data, SRS-
ECU determine the deployment of the side-airbags
and curtain airbags, then energizes appropriate
squib(s).
◇ SRS-ECU performs the diagnosis of the side impact

sensor internal components. If a malfunction oc-
curs, it sets the diagnosis code.

Substrate <Analogue G Sensor>
Housing
The analogue G sensor incorporated in the impact sen-
Analogue G sensor sors as shown in the figure 5-15 is a capacitive semi-
conductor type, and the construction and operation of
Fig. 5-15 the analogue G sensor in principle to detect the external
impact are as follows.

Deflection of Impact - Construction and operation -
movable electrode Proof mass
Refer to the figure 5-16, the analogue G
Beam Beam sensor consists of fixed electrode, proof
mass, movable electrode attached on the
Anchor Anchor proof mass, and beams which are able to
Fixed electrode deform elastically to support the proof mass.
Movable electrode When an impact is applied, the proof mass
moves, and the deflection of the movable
Fig. 5-16 electrodes happens, so the capacitance
caused of the fixed and the movable elec-
trodes varies. These capacitance variations
are converted to electrical signals using a
capacitor-voltage converter in the sensor
circuit, and the electrical signals are output
to the SRS-ECU as the detection result of
the impact.

5 - 7 Pub. No. PTAE1310

5. SUPPLEMENTAL RESTRAINT SYSTEM

9. Seat Belt Pre-tentioner
The seat belt pre-tensioner automatically winds the seat belt at the frontal collision to restrain the for-
ward travel of the passenger. The seat belt pre-tensioner operates in ahead of the airbag deployment
to restrain the forward travel of the passenger at the frontal collision, for achieving the effective airbag
function.

Fig. 5-17

<Seat Belt Pre-tensioner Operation>
1. When the seat belt pre-tensioner is inactivated, the clearance
between the roller and the sleeve is secured, and thus the sleeve
rotates freely. The spool which winds the seat belt rotates together
as with the sleeve.

Fig. 5-18

2. At the frontal collision, SRS-ECU which has detected the impact
exceeding the threshold from the front impact sensors is energized
to ignite the gas generator. Then the gas is generated, and the gas
pressure moves up the piston.

3. When the piston moves up, the rack gear of the piston is en-
gaged with the pinion gear of the pinion to rotate the pinion. When
the pinion rotates, the pinion is tilted to move the roller to the centre,
and the pinion, sleeve, and spool are incorporated.

Fig. 5-19 5-8
Pub. No. PTAE1310

5. SUPPLEMENTAL RESTRAINT SYSTEM
4. The gas pressure moves up the piston farther, and the pinion ro-
tates the spool to wind the seat belt.

Fig. 5-20

10. SRS-ECU
The SRS-ECU incorporates the analogue G-sensor for the side collision, in addition to the analogue
G-sensor and safing G-sensor for the frontal collision.
Upon a frontal collision, when the impact G is simultaneously detected by the front impact sensor in
the engine room, analogue G-sensor and safing G-sensor for the frontal collision in SRS-ECU, SRS-
ECU outputs the ignition signal to the driver’s and the front passenger’s airbag modules (squibs),
knee airbag modules (squibs).
Upon a side collision, when the lateral impact G is simultaneously detected by the analogue G-
sensor of side impact sensor and the G-sensor for side collision in SRS-ECU, the SRS-ECU outputs
the ignition signal to the side-airbag module (squib) and the curtain airbag module (squib) of the rele-
vant side that is subjected to the impact.
Also, SRS-ECU has the following functions that improve the system reliability.
◇ Power supply back-up function (back-up condenser) in preparation for the power supply malfunc-

tion upon a collision
◇ Booster function (DC-DC converter) in preparation for the battery voltage drop
◇ Diagnosis function that performs a system check

11. SRS Airbag Special Connector
To enhance the system reliability, a connector short-
circuit mechanism is integrated in the SRS-ECU con-
nector, air bag module connectors, clock spring con-
nector, and pre-tensioner connectors (black connector
"A" shown in the figure 5-21).

Fig. 5-21

5 - 9 Pub. No. PTAE1310

5. SUPPLEMENTAL RESTRAINT SYSTEM
<Connector Short-Circuit Mechanism>
This mechanism prevents the improper deployment of airbag module because of the current applica-
tion to the squib due to the static electricity when connectors between SRS-ECU and airbag modules
(squibs) are disconnected. When the connector is disconnected, the short spring short circuits the (+)
and (-) of squibs, and prevents the static electricity from generating the potential difference. This con-
nector mechanism is adopted for the following connectors.
◇ SRS-ECU connector
◇ Connector between the clock spring and body-side wiring harness
◇ Each airbag module connector
◇ Intermediate connector between curtain airbag module and SRS-ECU

Fig. 5-22

Pub. No. PTAE1310 5 - 10

5. SUPPLEMENTAL RESTRAINT SYSTEM

4. DIAGNOSIS FUNCTION

To improve the system reliability, SRS-ECU performs
the diagnostics of each part. If a malfunction is detected,
it lights up the SRS warning lamp, and stores the con-
tents as the corresponding diagnosis code. Also, to fa-
cilitate the system check, it has the following functions,
and the check can be performed using MUT-III.
◇ Diagnosis code set

◇ Service data output

◇ Actuator test

Fig. 5-23

1. Diagnosis Code Set

SRS-ECU performs a self-diagnosis on the following items. If a malfunction is detected, its content
(diagnosis code) is stored in the non-volatile memory (EEPROM*). Therefore, the diagnosis code will
not be erased even when the battery terminal is disconnected. The diagnosis code can be erased
using MUT-III.

Note *: EEPROM (Electrical Erasable & Programmable Read Only Memory): ROM that can be
programmed or erased electrically.

Code No. Diagnostic item

B1B00 Driver’s air bag module (1st squib) system (shorted to squib circuit earth)

B1B01 Driver’s air bag module (1st squib) system (shorted to squib circuit power supply)

B1B02 Driver’s air bag module (1st squib) system (open circuit of squib circuit)

B1B03 Driver’s air bag module (1st squib) system (short circuit between squib circuit terminals)

B1B04 Driver’s air bag module (2nd squib) system (shorted to squib circuit earth)

B1B05 Driver’s air bag module (2nd squib) system (shorted to squib circuit power supply)

B1B06 Driver’s air bag module (2nd squib) system (open circuit of squib circuit)

B1B07 Driver’s air bag module (2nd squib) system (short circuit between squib circuit terminals)

B1B08 Passenger’s (front) air bag module (1st squib) system (shorted to squib circuit earth)

B1B09 Passenger’s (front) air bag module (1st squib) system (shorted to squib circuit power supply)

B1B0A Passenger’s (front) air bag module (1st squib) system (open circuit of squib circuit)

B1B0B Passenger’s (front) air bag module (1st squib) system (short circuit between squib circuit terminals)

B1B0C Passenger’s (front) air bag module (2nd squib) system (shorted to squib circuit earth)

B1B0D Passenger’s (front) air bag module (2nd squib) system (shorted to squib circuit power supply)

B1B0E Passenger’s (front) air bag module (2nd squib) system (open circuit of squib circuit)

B1B0F Passenger’s (front) air bag module (2nd squib) system (short circuit between squib circuit terminals)

B1B10 Driver’s knee air bag module (squib) system (shorted to squib circuit earth)

B1B11 Driver’s knee air bag module (squib) system (shorted to squib circuit power supply)

B1B12 Driver’s knee air bag module (squib) system (open circuit of squib circuit)

B1B13 Driver’s knee air bag module (squib) system (short circuit between squib circuit terminals)

B1B18 Left curtain air bag module (squib) system (shorted to squib circuit earth)

B1B19 Left curtain air bag module (squib) system (shorted to squib circuit power supply)

B1B1A Left curtain air bag module (squib) system (open circuit of squib circuit)

B1B1B Left curtain air bag module (squib) system (short circuit between squib circuit terminals)

B1B20 Right curtain air bag module (squib) system (shorted to squib circuit earth)

B1B21 Right curtain air bag module (squib) system (shorted to squib circuit power supply)

B1B22 Right curtain air bag module (squib) system (open circuit of squib circuit)

B1B23 Right curtain air bag module (squib) system (short circuit between squib circuit terminals)

B1B70 Malfunction of G-sensor inside left front impact sensor

B1B71 Malfunction of G-sensor inside right front impact sensor

B1B72 Malfunction of G-sensor inside left side impact sensor

B1B75 Malfunction of G-sensor inside right side impact sensor

5 - 11 Pub. No. PTAE1310

5. SUPPLEMENTAL RESTRAINT SYSTEM

(Be continued from previous page)

Code No. Diagnostic item

B1BA5 SRS-ECU squib count mismatch
B1BC7 SRS-ECU (record data full) system
B1C27 Left side-airbag module (squib) system (shorted to squib circuit earth)
B1C28 Left side-airbag module (squib) system (shorted to squib circuit power supply)
B1C29 Left side-airbag module (squib) system (open circuit of squib circuit)
B1C2A Left side-airbag module (squib) system (short circuit between squib terminals)
B1C2B Right side-airbag module (squib) system (shorted to squib circuit earth)
B1C2C Right side-airbag module (squib) system (shorted to squib circuit power supply)
B1C2D Right side-airbag module (squib) system (open circuit of squib circuit)
B1C2E Right side-airbag module (squib) system (short circuit between squib terminals)
B1C38 Seat belt pre-tensioner (driver’s side) (squib) system (shorted to squib circuit earth)
B1C39 Seat belt pre-tensioner (driver’s side) (squib) system (shorted to squib circuit power supply)
B1C3A Seat belt pre-tensioner (driver’s side) (squib) system (open circuit of squib circuit)
B1C3B Seat belt pre-tensioner (driver’s side) (squib) system (short circuit between squib circuit terminals)
B1C47 Seat belt pre-tensioner (passenger’s side) (squib) system (shorted to squib circuit earth)
B1C48 Seat belt pre-tensioner (passenger’s side) (squib) system (shorted to squib circuit power supply)
B1C49 Seat belt pre-tensioner (passenger’s side) (squib) system (open circuit of squib circuit)
B1C4A Seat belt pre-tensioner (passenger’s side) (squib) system (short circuit between squib circuit termi-

nals)
B210D Battery abnormal low voltage
B212C IG1 power supply open circuit (fuse No. 12 circuit)
B212D IG1 power supply open circuit (fuse No. 18 circuit)
B2207 Occupant restraint controller internal 1
B2208 Occupant restraint controller internal 2
B2209 Occupant restraint controller internal 3
B220A Occupant restraint controller internal 4
B220B Occupant restraint controller firing stored energy
B220C Occupant restraint controller accelerometer 1 internal
B220D Occupant restraint controller accelerometer 2 internal
U0019 Bus off
U0141 ETACS CAN timeout
U0155 Combination meter CAN timeout
U0164 A/C -ECU CAN timeout
U0168 KOS/WCM CAN timeout
U0170 Left front impact sensor communication error
U0171 Right front impact sensor communication error
U0172 Left side impact sensor communication error
U0175 Right side impact sensor communication error
U0184 Audio CAN timeout
U1414 Defective coding data
U1415 Coding data not written

2. Data List Output
Using MUT-III, the service data can be read.

3. Actuator Test
Using MUT-III, the actuator can be forcibly operated.

Pub. No. PTAE1310 5 - 12

5. SUPPLEMENTAL RESTRAINT SYSTEM

5. INSPECTION & SERVICE PROCEDURES
1. Service Precautions
In order to avoid injury to yourself or others from accidental deployment of the SRS air bag during
servicing, read and carefully follow all the precautions and procedures.

(1) Never attempt to repair the following components:
◇ SRS-ECU
◇ Driver’s air bag module
◇ Clock spring
◇ Passenger’s (front) air bag module
◇ Knee air bag module
◇ Curtain air bag module
◇ Front seat assembly incorporating side-airbag module
◇ Seat belt with pre-tensioner
◇ Front impact sensor
◇ Side impact sensor

Fig. 5-24 (2) Before maintenance, wait for 60 seconds or more af-
ter the disconnection of the battery (-) terminal. Wrap the
disconnected (-) terminal with tape for insulation. The
condenser inside SRS-ECU keeps a voltage necessary
to expand the air bag for a certain period even after the
IG power is turned OFF. Therefore, if any operation is
performed before the period elapses, it may cause seri-
ous damage.

(3) If the influence of heat is suspected during painting
work, remove the following parts:
◇ 93°C or higher SRS-ECU, air bag module, clock

spring, front impact sensor, side impact sensor
◇ 90 °C or higher Seat belt with pre-tensioner

(4) After the maintenance of the SRS air bag and seat
belt with pre-tensioner is completed, be sure to delete the
diagnosis code and check whether the SRS warning
lamp lights up.

<SRS Warning Lamp Check>
(1) Check that the SRS warning lamp is illuminated
when the ignition switch is turned ON.

(2) Check that the lamp is extinguished after the approx-
imately 6 to 8 seconds illumination. Check that the
warning lamp is extinguished afterward.

(3) Except the above, the SRS system is abnormal.
Thus, check the diagnosis code with MUT-III.

Fig. 5-25

5 - 13 Pub. No. PTAE1310

5. SUPPLEMENTAL RESTRAINT SYSTEM

2. Post-Collision Diagnosis
Perform the inspection and service on post-collision vehicles according to the procedures below.

(1) Diagnosis Code Check
1. Connect M.U.T.-III to the diagnosis connector.
2. Use M.U.T.-III to read all the diagnosis codes.
3. Erase the stored memory of diagnosis code, and then wait for 45 seconds or more to read the di-
agnosis code again. However, when the air bag has been deployed or if SRS-ECU is judged to be
failure, do not erase the stored memory of diagnosis code.

(2) Driver’s and Front Passenger’s Airbags are Deployed
1. Replace the following parts with new ones.
◇ SRS-ECU
◇ Driver’s air bag module
◇ Passenger’s (front) air bag module
◇ Knee air bag module (Refer to).
◇ Seat belt with pre-tensioner
◇ Front impact sensor
◇ Instrument panel assembly

2. Check the following parts. If there is an abnormality, replace with new parts.
◇ Clock spring
◇ Steering wheel, steering column assembly

3. Check the wiring harness for binding, the connector for damage, and the terminal for deformation.

(3) Side and Curtain Airbags are Deployed
1. Replace the following parts with new ones.
◇ SRS-ECU
◇ Front seatback pad and frame assembly
◇ Curtain air bag module
◇ Side impact sensor
◇ Headlining
◇ Front pillar trim, upper centre pillar trim, rear pillar trim

2. Check the wiring harness for binding, the connector for damage, and the terminal for deformation.

(4) Airbag not Deployed Because of Low-Speed Collision
Check the SRS air bag components and seat belt pre-tensioner according to the following proce-
dures.
1. If a crack, deformation, or others are visually detected to the SRS air bag components or pre-

tensioner, replace them with new parts.
2. Check the operation of seat belt. If the seat belt cannot be drawn out, replace the seat belt with a

new one.

Pub. No. PTAE1310 5 - 14

5. SUPPLEMENTAL RESTRAINT SYSTEM

3. Clock Spring Installation

Caution ◇ If the centre of the clock spring is not correctly aligned, the steering wheel may not be turned

fully or the cable inside the clock spring may be broken, causing the SRS airbag to be inopera-
tive or operated incorrectly.

◇ When aligning the clock spring neutral position mark, perform with the clock spring inde-

pendently. If performed with the steering wheel sensor installed, the steering wheel sensor may
be damaged.

Fig. 5-26 <Alignment of mating marks>
(1) Turn the clock spring clockwise fully.
(2) Turn the clock spring anti-clockwise approximately
three and 1/2 turns to align the mating marks.
(3) Check that the white roller can be seen from the win-
dow for checking the neutral point when the mating
marks are aligned.

If the white roller cannot be seen or black roller
Note can be seen, the neutral point is not aligned cor-

rectly.

(4) Install the clock spring to the column switch.

4. Freeze Frame Data

The freeze frame data can be checked by using M.U.T.-III.
When detecting the trouble and storing the diagnosis code, the SRS-ECU stores the following service
data at the moment. By analyzing the freeze frame data, the troubleshooting can be performed more
efficiently.

No. Item Contents Unit
1 Odometer km
Total driving distance after the diagnosis code is
2 Ignition cycle generated. Number of counts is
displayed.
Number of times the ignition switch is turned "ON" min
or "LOCK (OFF)" after the past failure transition.

4 Current trouble accu- Cumulative time for current malfunction of diagno-

mulative time sis code

5. Data List Reference Table
The following items of the ECU input data can be read using MUT-III.

No. Display on MUT-III Check conditions Normal conditions
OFF
1 SRS warning lamp Ignition switch: ON
"ON" request After warning lamp pre-check ON

Ignition switch: ON
During warning lamp pre-check

6. Actuator Test Reference Table
The following actuators can be forcibly operated using MUT-III.

No. Item Test item Driven component
ON
1 SRS warning lamp SRS warning lamp illumination

5 - 15 Pub. No. PTAE1310

5. SUPPLEMENTAL RESTRAINT SYSTEM

6. KNOWLEDGE CHECK
Regarding the following sentences of Supplemental Restraint System, identify which ones are correct
or incorrect, and make the required correction to the wrong portion of the incorrect sentence.

(1) SLS airbag is a system that is effective with the seat belt fastened, and it is designed as a supple-
mental system of the seat belt.

(2) Dual stage airbags have been adopted to the driver’s and the front passenger’s sides. Depending
on the severity of impact, the airbag inflates the cushion airbag in two stages.

(3) Driver’s knee airbag is activated when an impact exceeds the threshold upon a lateral collision,
and the cushion airbag is instantaneously inflated for better protection of the driver.

(4) Side-airbag is activated when an impact exceeds the threshold upon a side collision, and the
cushion airbag is instantaneously inflated to protect the chest area of the front seat passengers.

(5) Curtain airbag is activated simultaneously with the side-airbag upon a side collision to protect the
legs of the front seat and second seat passengers.

(6) Inflator generates gas to deploy an airbag module of which is harmless to the human body.

(7) Seat belt pre-tensioner is activated independently of the deployment of driver’s and the front pas-
senger’s airbags in case of a frontal collision.

(8) On the seat belt with pre-tentioner, seat belts are pulled in to eliminate the slack upon a collision,
thus improving the initial occupant restraint, and reducing the travel distance of the occupants.

(9) It is allowed to disassemble the SRS airbag components and seat belt with pre-tensioner. Also,
do not apply any impact on them.

(10) SRS-ECU uses data of the front impact sensor (in engine compartment) and G-sensor (in SRS-
ECU) to calculate collision severity during frontal collision. SRS-ECU judges necessity of 2nd deploy-
ment of the dual stage airbag based on the calculated collision severity.

(11) SRS-ECU uses data of the front impact sensor and G-sensor (in SRS-ECU) to calculate collision
severity, during side collision. SRS-ECU judges necessity of side-airbag and curtain airbag based on
the calculated collision severity.

(12) The inflator of driver’s airbag module is equipped with two squib connectors to deploy the air bag
in two stages.

(13) The front passenger’s airbag module consists of an airbag, and their fasteners. The airbag is
made from nylon and inflates by the compressed air from the inflator. The inflator has two squib con-
nectors to deploy the airbag in two stages.

(14) The side-airbag module is installed in the outer side supports of the driver’s and front passen-
ger’s seatbacks. The side-airbags help protect the occupants regardless of the seat position and
seatback angle.
(15) Upon a lateral collision, when the impact G is simultaneously detected by the front impact sensor
in the engine room, analogue G-sensor and safing G-sensor for the frontal collision in SRS-ECU,
SRS-ECU outputs the ignition signal to the driver’s and the front passenger’s airbag modules, knee
airbag modules.

(16) Upon a side collision, when the lateral impact G is simultaneously detected by the analogue G-
sensor of side impact sensor and the G-sensor for side collision in SRS-ECU, the SRS-ECU outputs
the ignition signal to the side-airbag module and the curtain airbag module of the relevant side that is
subjected to the impact.

(17) Connector short-circuit mechanism prevents the improper deployment of airbag module by the
current application to the squib due to the counter-electromotive force when connectors between
SRS-ECU and airbag modules are disconnected.

(18) To enhance the system reliability, a connector short-circuit mechanism is integrated in the SRS-
ECU connector, air bag module connectors, clock spring connector, and pre-tensioner connectors.

(19) If a malfunction is detected, SRS-ECU lights up the ABS warning lamp.

(20) Diagnosis code stored in the SRS-ECU will not be erased even when the battery terminal is dis-
connected. The diagnosis code can be erased using MUT-III.

Pub. No. PTAE1310 5 - 16