ISUZU Service manual 4JA1-4JH1-TC

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–47
ECM WIRING DIAGRAM (2/7)

6E–48 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
ECM WIRING DIAGRAM (3/7)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–49
ECM WIRING DIAGRAM (4/7)

6E–50 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
ECM WIRING DIAGRAM (5/7)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–51
ECM WIRING DIAGRAM (6/7)

6E–52 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
ECM WIRING DIAGRAM (7/7)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–53

ECM CONNECTOR PIN ASSIGNMENT & OUTPUT SIGNAL

4JA1-TC ECM CONNECTOR PIN ASSIGNMENT & OUTPUT SIGNAL
View Looking Into ECM Case

Signal or Continuity Tester Position

Pin B/Box Pin Function Wire Key SW Key SW Engine Engine ECM Range (+) (-)
No. No. Color Off On Idle 2000rpm Connec- Ohm
1 GND
11 ECM Ground BLK Continuity - - - tion
with 2 GND
Discon-
ground nect 3 GND
- -
22 ECM Ground BLK Continuity - - - Discon- Ohm - -
with nect 27
GND
ground

3 3 Battery Power Supply BLU/ Less than 10-14V Connect DC V

RED 1V

25 25 No Connection - - - - - --

26 26 No Connection - - - - - --

27 27 Engine Speed Output LGN - - Approx. Approx. Connect AC V
(To Tacho Meter)
23Hz by 67Hz by

wave form wave form

or approx. or approx.

6.3V 6.8V

28 28 No Connection - - - - - - - --

29 29 No Connection - - - - - - - --

30 30 Brake Switch 1 Signal GRN Less than Pedalisnotstepped on:Lessthan 1V Connect DC V 30 GND
1V Pedal is stepped on: 10-14V

31 31 Clutch Switch Signal YEL Less than Pedal is no t ste pped o n: 10-14V Connect DC V 31 GND

(MT Only) 1V Pedal is stepped on: Less than 1V

32 32 No Connection - - - - - - - --

33 33 A/C ON Signal Relay GRN/ Less than A/C request switch is turned on: 10- Connect DC V 33 GND

YEL 1V 14V

A/C request switch is turned off: Less

than 1V

34 34 No Connection - - - - - - - --

35 35 To Data Link Connec- YEL - - - - - - --

tor No. 6 & Immobi-

lizer Control Unit (ICU

B8)

36 36 No Connection - - -- - - - - -
-- - - - -
37 37 No Connection - - Less than 1V - Connect DC V 38 49

38 38 Throttle Position Sen- GRN/ Less than 10-14V Approx.
0.5V
sor (TPS) Output Sig- ORG 1V --

nal

39 39 Key Switch Input Sig- WHT Less than Connect DC V 39 GND

nal Via Engine Fuse 1V

40 40 No Connection - - - - - --

6E–54 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

Signal or Continuity Tester Position

Pin B/Box Pin Function Wire Key SW Key SW Engine Engine ECM Range (+) (-)
No. No. Color Off On Idle 2000rpm Connec- DC V 41 GND
A/C Compressor
41 41 Relay WHT/ Less than 10-14V A/C comp. is operated: tion 42 GND
GRN 1V Le ss tha n 1V 43 GND
Connect
GRN/ Less than A/C comp. is not oper-
YEL 1V ated: 10 - 14V
ORG/
42 42 Check Engine Lamp BLU Less than Lamp isturned on: Lessthan 1V Connect DC V
1V Lamp is turned off: 10-14V Connect DC V

43 43 Glow Lamp Lamp isturned on: Lessthan 1V
Lamp is turned off: 10-14V

44 44 No Connection - - --- - - --
10-14V Connect DC V 45 GND
45 45 To Data Link Connec- BLU Less than
---
tor No. 6 1V ---
---
46 46 No Connection - - --- - - - -
- - -
47 47 No Connection - - --- - - - -
--- Ohm 38 49
48 48 No Connection - - --- -
---
49 49 Throttle Position Sen- BLK/ Idle: --- Discon-
--- nect
sor (TPS) Ground GRN Approx. ---

0.4K ohm / Approx. 5V

WOT:

Approx.

4.0K ohm

50 50 No Connection - - - - - -
- - - -
51 51 No Connection - - - - - -
- - - -
52 52 No Connection - - - - - -
- - - -
53 53 No Connection - - - - - -
Connect DC V 57 49
54 54 No Connection - -

55 55 No Connection - -

56 56 No Connection - -

57 57 Throttle Position Sen- RED/ Less than

sor (TPS) Power Sup- GRN 1V

ply

58 58 ECM Relay BLU/ 10-14V Less than 1V Connect DC V 58 GND
BLK

59 59 No Connection - - - - - - - --

60 60 No Connection - - - - - - - --

61 61 No Connection - - - - - - - --

62 62 No Connection - - - - - - - --

63 63 ECM Power Supply Less than 10-14V - DC V 63 GND
1V

64 64 No Connection - - - - - - - --

65 65 Brake Switch 2 Signal WHT/ Less than Pedal is no t ste pped o n: 10-14V Connect DC V 65 GND

BLK 1V Pedal is stepped on: Less than 1V

66 66 No Connection - - - - - - - --

67 67 No Connection - - - - - - - --

68 68 Vehicle Speed Sen- YEL/ - Approx. 14.5Hz by wave form or Connect AC V 68 GND

sor (VSS) GRN approx. 6.0V at vehicle speed 20km/h

69 69 Idle Switch GRN/ Less than Pedalisnotstepped on:Lessthan 1V Connect DC V 69 GND
BLK 1V Pedal is stepped on: Approx. 5V

70 70 No Connection - - - - - - - --

71 71 No Connection - - - - - - - --

72 72 No Connection - - - - - - - --

73 73 No Connection - - - - - - - --

74 74 No Connection - - - - - - - --

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–55

Signal or Continuity Tester Position

Pin B/Box Pin Function Wire Key SW Key SW Engine Engine ECM Range (+) (-)
No. No. No Connection Color Off On Idle 2000rpm Connec- - - -

75 75 -- - - - tion

-

76 76 No Connection - - - - - - - --

77 77 No Connection - - - - - - - --

78 78 No Connection - - - - - - - --

79 79 No Connection - - - - - - - --

80 80 No Connection - - - - - - - --

81 81 No Connection - - - - - - - --

82 82 No Connection - - - - - - - --

83 83 Mass Air Flow (MAF) WHT/ Less than Approx. 5V Connect DC V 83 92

Sensor Power Supply RED 1V

84 84 Intake Air Tempera- BLK/ Less than 0 deg. C: Approx. 3.6V / 20 deg. C: Connect DC V 84 92
ture (IAT) Sensor Sig- BLU 1V Approx. 2.6V / 40 deg. C: Approx.
nal 1.7V / 60 deg. C: 1.1V / 80 deg. C:
0.7V

85 85 No Connection - - - - - - - --

86 86 No Connection - - - - - - - --

87 87 Neutral Switch BLK/ Less than In neutral: Less than 1V Connect DC V 87 GND
WHT 1V Other than neutral: 10-14V

88 88 Mass Air Flow (MAF) GRN/ Less than Approx. 1V Approx. Approx. Connect DC V 88 92

Sensor Signal RED 1V 1.8V 2.5V

89 89 Engine Coolant Tem- GRY Less than 0 deg. C: Approx. 4.4V / 20 deg. C: Connect DC V 89 93

perature (ECT) Sen- 1V Approx. 3.8V / 40 deg. C: Approx.

sor Signal 2.9V / 60 deg. C: 2.1V / 80 deg. C:

1.4V

90 90 CKP Sensor Signal RED - - Approx. Approx. Connect AC V 90 98

47Hz by 134Hz by

wave form wave form

or approx.

1.1V

91 91 CKP Sensor Output PNK - - Approx. Approx. Connect AC V 91 GND
To Pump Control Unit 47Hz by 134Hz by
(PSG) No.8 wave form wave form
or approx.
0.7V

92 92 Mass Air Flow (MAF) BLK/ Continuity - - - Connect Ohm 92 GND

Sensor Ground RED with

ground

93 93 Engine Coolant Tem- BLK/ Continuity - - - Connect Ohm 93 GND

perature (ECT) Sen- PNK with

sor Ground ground

94 94 Glow Relay BLK/ Less than Glow system is operated: Less than Connect DC V 94 GND

RED 1V 1V

Glow system is not operated: 10 - 14V

95 95 No Connection - - - - - - - --

96 96 No Connection - - --- - - --
97 97 EGR EVRV - - - --
BLK/ - Approx. 140Hz by wave
ORG form when EVRV is
operated

98 98 CKP Sensor Ground WHT Continuity - - - Connect Ohm 98 GND

with

ground

99 99 CAN (Controller Area BLU - - - - - - --

Network) to PSG No.1

100 100 CAN (Controller Area YEL - - - - - - --

Network) to PSG No.2

6E–56 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

Signal or Continuity Tester Position

Pin B/Box Pin Function Wire Key SW Key SW Engine Engine ECM Range (+) (-)
No. No. Color Off On Idle 2000rpm Connec-

101 101 CKP Sensor Shield BLK Continuity -- - tion Ohm 101 GND
Line with
Connect
ground

102 102 No Connection - - -- - - - --
-- - - - --
103 103 No Connection - - -- - - - --
-- - - - --
104 104 No Connection - -

105 105 Solenoid Valve Shut ORG -

Off (MAB) Output Sig-
nal to PSG No.5

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–57

PSG CONNECTOR PIN ASSIGNMENT & OUTPUT SIGNAL
View Looking Into PSG Case

Signal or Continuity Tester Position

Pin B/ Pin Function Wire Key SW Key SW Engine Engine ECM & Rang (+) (-)
No. Box Color Off On Idle 2000rpm PSG Con- e 1
RED 99
No. Continu- - - - nection Ohm (EC
WHT ity M)
1 99 CAN (Controller Area Discon-
Network) to ECM - between nect
- ECM &
No.99 ORG
PSG
2 100 CAN (Controller Area BLK - - - Discon- Ohm 2 100
Network) to ECM BLU/ Continu- nect (EC
No.100 RED ity M)
PNK
3- No Connection between --- - ---
- ECM &
4- No Connection --- - ---
PSG
5 105 Solenoid Valve Shut - - - Discon- Ohm 5 105
Off (MAB) Output -
Signal to ECM nect (EC
No.105 - M)

6- Ground Continu- - - - Discon- Ohm 6 GND
ity nect

7 - Battery Power Sup- between 10-14V Discon- Ohm 7 GND
ply ECM & nect

8 91 CKP Sensor Output PSG - - - Discon- Ohm 8 91
ECM No.91 to Pump
Control Unit (PSG) Continu- nect (EC
ity with
ground M)

9- No Connection Less --- - ---
than 1V

Continu-
ity

between
ECM &

PSG

-

6E–58 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

4JH1-TC ECM CONNECTOR PIN ASSIGNMENT & OUTPUT SIGNAL
View Looking Into ECM Case

Signal or Continuity Tester Position

Pin B/ Pin Function Wire Key SW Key SW Engine Engine ECM Ran (+) (-)
No. Box ECM Ground Color Off On Idle 2000rpm Connec- ge
BLK
No. Continu- tion
BLK ity with
11 ground - - - Discon- Ohm 1 GND
BLU/ Continu- nect
RED ity with
22 ECM Ground ground - - - Discon- Ohm 2 GND
- Less nect
- than 1V
3 3 Battery Power Sup- LGN 10-14V Connect DC V 3 GND
ply -
- -
25 25 No Connection - - - - - ---
GRN
26 26 No Connection - - - - - ---
YEL -
27 27 Engine Speed Output - - Approx. Approx. Connect AC V 27 GND
(To Tacho Meter)
GRN/ 23Hz by 67Hz by
YEL
wave wave
-
YEL form or form or

- approx. approx.

6.3V 6.8V

28 28 No Connection - - - - ---

29 29 Throttle Position Sig- Approx. 140Hz by wave form (Idle: - ---
nal To TCM (A16) Off duty 10% / WOT: Off duty 90%)
(AT Only)

30 30 Brake Switch 1 Sig- Less Pedal is not stepped on: Less than Connect DC V 30 GND
nal
than 1V 1V

Pedal is stepped on: 10-14V

31 31 Clutch Switch Signal Less Pedal is no t steppe d on: 10-14V Connect DC V 31 GND
(MT Only)
than 1V Pedal is stepped on: Less than 1V

32 32 No Connection - - - - - ---

33 33 A/C ON Signal Relay Less A/C request switch is turned on: 10- Connect DC V 33 GND

than 1V 14V

A/C request switch is turned off:

Less than 1V

34 34 No Connection - - - - - ---

35 35 To Data Link Con- - - - - - ---
nector No. 6 & Immo-
bilizer Control Unit
(ICU B8)

36 36 No Connection - - - - - ---

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–59

Signal or Continuity Tester Position

Pin B/ Pin Function Wire Key SW Key SW Engine Engine ECM Ran (+) (-)
No. Box Color Off On Idle 2000rpm Connec- ge
- -
No. - - tion - 38 49
DC V
37 37 No Connection - Less -- Approx. -
than 1V Less than 1V 0.5V
38 38 Throttle Position GRN/ Connect

Sensor (TPS) Out- ORG

put Signal

39 39 Key Switch Input Sig- WHT Less 10-14V Connect DC V 39 GND
than 1V -
nal Via Engine Fuse
- GND
40 40 No Connection - --- - - -
Less Connect DC V 41 GND
41 41 A/C Compressor WHT/ than 1V 10-14V A/C comp. is oper- GND
Relay GRN ated:Lessthan1V Connect DC V 42
Less A/C comp. is not oper- Connect DC V 43 -
than 1V - GND
ated: 10 - 14V - - 45
Less Connect DC V -
42 42 Check Engine Lamp GRN/ than 1V Lampisturned on:Lessthan 1V -
Lamp is turned off: 10-14V -
YEL - 49

43 43 Glow Lamp ORG/ Less Lampisturned on:Lessthan 1V -
BLU than 1V Lamp is turned off: 10-14V -
-
44 44 No Connection - - --- -
-
45 45 To Data Link Con- BLU - 10-14V -
nector No. 6 -
- 49
46 46 No Connection - - - - - --
Idle:
47 47 No Connection - Approx. - - - - --

48 48 No Connection - 0.4K - - - - --
ohm /
49 49 Throttle Position BLK/ WOT: - - - Discon- Ohm 38
GRN Approx. nect
Sensor (TPS) 4.0K
Ground ohm

50 50 No Connection - - --- - - -
--- - - -
51 51 No Connection - - --- - - -
--- - - -
52 52 No Connection - - --- - - -
--- - - -
53 53 No Connection - - --- - - -
Connect DC V 57
54 54 No Connection - - Approx. 5V

55 55 No Connection - -

56 56 No Connection - -

57 57 Throttle Position RED/ Less
than 1V
Sensor (TPS) Power GRN

Supply

58 58 ECM Relay BLU/ 10-14V Less than 1V Connect DC V 58 GND
BLK

59 59 No Connection - - - - - - ---
- - - - - ---
60 60 No Connection - - - - - - ---
- - - - - ---
61 61 No Connection -

62 62 No Connection -

6E–60 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

Signal or Continuity Tester Position

Pin B/ Pin Function Wire Key SW Key SW Engine Engine ECM Ran (+) (-)
No. Box Color Off On Idle 2000rpm Connec- ge

No. - Less tion
than 1V
63 63 ECM Power Supply - 10-14V - DC V 63 GND
WHT/ -
64 64 No Connection BLK Less - - - - ---
than 1V
65 65 Brake Switch 2 Sig- - Pedal is no t steppe d on: 10-14V Connect DC V 65 GND
nal - -
YEL/ - Pedal is stepped on: Less than 1V
GRN -
66 66 No Connection - - - - ---
GRN/ Less
67 67 No Connection BLK than 1V - - - - ---

68 68 Vehicle Speed Sen- - - Approx. 14.5Hz by wave form or Connect AC V 68 GND
sor (VSS) - - approx. 6.0V at vehicle speed
- - 20km/h
- -
69 69 Idle Switch - - Pedal is not stepped on: Less than Connect DC V 69 GND
- - 1V
- -
- - Pedal is stepped on: Approx. 5V
- -
70 70 No Connection - - - - - - ---
- -
71 71 No Connection - - - - - - ---
WHT/ Less
72 72 No Connection BLU than 1V - - - - ---

73 73 No Connection WHT/ - - - - ---
RED
74 74 No Connection - - - - ---
BLK/
75 75 No Connection BLU - - - - ---

76 76 No Connection RED/ - - - - ---
BLU
77 77 No Connection - - - - ---
-
78 78 No Connection BLK/ - - - - ---
WHT
79 79 No Connection - - - - ---
GRN/
80 80 No Connection RED - - - - ---

81 81 No Connection - - - - ---

82 82 Boost Pressure Sen- Approx. 5V Connect DC V 82 93

sor (High Altitude
Spec. Only)

83 83 Mass Air Flow (MAF) Less Approx. 5V Connect DC V 83 92
Sensor Power Sup- than 1V
ply

84 84 Intake Air Tempera- Less 0 deg. C: Approx. 3.6V / 20 deg. C: Connect DC V 84 92
ture (IAT) Sensor than 1V Approx. 2.6V / 40 deg. C: Approx. Connect DC V 85 93
1.7V / 60 deg. C: 1.1V / 80 deg. C:
Signal Less
than 1V 0.7V
85 85 Manifold Pressure
Sensor (High Alti- ---

tude Spec. Only)

86 86 No Connection - - - - - ---

87 87 Neutral Switch Less In neutral (A/T: P or N): Less than Connect DC V 87 GND

than 1V 1V

Other than neutral (A/T: other than

P or N): 10-14V

88 88 Mass Air Flow (MAF) Less Approx. Approx. Approx. Connect DC V 88 92
Sensor Signal than 1V 1V 1.8V 2.5V

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–61

Signal or Continuity Tester Position

Pin B/ Pin Function Wire Key SW Key SW Engine Engine ECM Ran (+) (-)
No. Box Color Off On Idle 2000rpm Connec- ge
GRY
No. tion
RED
89 89 Engine Coolant Tem- Less 0 deg. C: Approx. 4.4V / 20 deg. C: Connect DC V 89 93
PNK than 1V Approx. 3.8V / 40 deg. C: Approx.
perature (ECT) Sen- 2.9V / 60 deg. C: 2.1V / 80 deg. C:
sor Signal BLK/
RED 1.4V
BLK/
90 90 CKP Sensor Signal PNK - - Approx. Approx. Connect AC V 90 98

BLK/ 47Hz by 134Hz by
RED
wave wave
-
BRW/ form form or
RED
BLK/ approx.
ORG
WHT 1.1V

91 91 CKP Sensor Output BLU - - Approx. Approx. Connect AC V 91 GND
To Pump Control Unit
(PSG) No.8 YEL 47Hz by 134Hz by

BLK wave wave

- form form or
-
- approx.
ORG
0.7V

92 92 Mass Air Flow (MAF) Continu- - - - Connect Ohm 92 GND
Sensor Ground
ity with

ground

93 93 Engine Coolant Tem- Continu- - - - Connect Ohm 93 GND
perature (ECT) Sen-
sor & Manifold ity with
Pressure Sensor
Ground ground

94 94 Glow Relay Less Glow system is operated: Less than Connect DC V 94 GND

than 1V 1V

Glow system is not operated: 10 -

14V

95 95 No Connection - - - - - ---

96 96 Turbocharger Waste- -- Wave form - ---
gate Control EVRV

97 97 EGR EVRV -- Approx. 140Hz by - ---
wave form when Connect Ohm 98 GND
98 98 CKP Sensor Ground Continu- - EVRV is operated
ity with -
ground --

99 99 CAN (Controller Area - - - - ---
Network) to PSG
No.1 - - - - - ---

100 100 CAN (Controller Area Continu- - - - Connect Ohm 101 GND
Network) to PSG
No.2 ity with

101 101 CKP Sensor Shield
Line

ground

102 102 No Connection - - - - - ---

103 103 No Connection - - - - - ---

104 104 No Connection - - - - - ---

105 105 Solenoid Valve Shut - - - - - ---

Off (MAB) Output
Signal to PSG No.5

6E–62 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

PSG CONNECTOR PIN ASSIGNMENT & OUTPUT SIGNAL
View Looking Into PSG Case

Signal or Continuity Tester Position

Pin B/ Pin Function Wire Key SW Key SW Engine Engine ECM & Rang (+) (-)
No. Box Color Off On Idle 2000rp PSG Con- e
RED
No. m nection
WHT -
1 99 CAN (Controller Area Continu- - - Discon- Ohm 1 99
Network) to ECM - ity - nect (ECM
- - -
No.99 ORG between - )
ECM & - - -
2 100 CAN (Controller Area BLK - - - Discon- Ohm 2 100
Network) to ECM BLU/ PSG - - nect (ECM
No.100 RED - )
PNK Continu- - -
3- No Connection ity 10-14V - - - --
- - -
4- No Connection between - - - Ohm --
ECM & -
5 105 Solenoid Valve Shut - Discon- 5 105
Off (MAB) Output PSG nect (ECM
Signal to ECM )
No.105 -

6- Ground - Discon- Ohm 6 GND
nect
Continu- 7 GND
7 - Battery Power Sup- ity Discon- Ohm
ply nect Ohm 8 91
between (ECM
8 91 CKP Sensor Output ECM & Discon- )
ECM No.91 to Pump nect
Control Unit (PSG) PSG

9- No Connection Continu- - ---
ity with
ground

Less
than 1V

Continu-
ity

between
ECM &

PSG

-

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–63

Crankshaft Position (CKP) Sensor Reference Wave Form Crankshaft Position (CKP) Sensor & TDC Output Signal
Reference Wave Form

0V CH1
0V
Measurement Terminal: 90(+) 98(-)
Measurement Scale: 20V/div 2ms/div CH2
Measurement Condition: Approximately 2000rpm 0V
Engine Speed Output Signal Reference Wave Form
Measurement Terminal: CH1: 90(+) / CH2: 91(+) GND(-)
Measurement Scale: CH1: 50V/div / CH2: 10V/div 1ms/div
Measurement Condition: Approximately 2000rpm
Vehicle Speed Sensor (VSS) Reference Wave Form

0V 0V

Measurement Terminal: 27(+) GND(-) Measurement Terminal: 68(+) GND(-)

Measurement Scale: 5V/div 10ms/div Measurement Scale: 5V/div 50ms/div
Measurement Condition: Approximately 2000rpm Measurement Condition: Approximately 20km/h

6E–64 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

GENERAL DESCRIPTION FOR ECM AND management system.
SENSORS
• Engine Control Module (ECM)
Engine Control Module (ECM)
• Pump Control Unit (PSG) = Pumpen Steuer Great
(German)

The engine control module (ECM) is located flower The pump control unit (PSG) receives signals from the
panel just under the passenger's seat. sensors inside the pump to determine the cam ring
The fuel quantity and injection timing related functions rotation angle, the pump speed and the fuel
are controlled by the pump control unit (PSG). temperature .
The engine control module (ECM) performs the These values are then compared to the desired values
following functions. sent by the engine control module (ECM) such as the
desired injection timing and the desired fuel injection
• Control of the exhaust gas re-circulation (EGR) quantity.
The engine control module (ECM) processes all engine
• Control of the quick on start (QOS) glow control data and data regarding the surrounding environment
system received from external sensors to perform any engine
side adjustments.
• Control of the A/C compressor Maps for both are encoded in both control units. The
control units input circuit process sensor data.
• Execution of the immobilizer function A Microprocessor then determines the operating
conditions and calculates set values for optimum
Pump Control Unit (PSG) & Data Exchange running.
Between Control Module The interchange of data between the engine control
module (ECM) and the pump control unit (PSG) is
Self Diagnosis / Interface / Signal perfumed via a CAN-bus system. The abbreviation CAN
stands for Controller Area Network. By having two
Engine Speed Engine To High Pressure Solenoid separate control modules, the high pressure solenoid
Accelerator Pedal Control Cam Ring Rotational Angle valve. This prevents the discharge of any disturbing
Intake Air Temperature Module Fuel Temperature signals.
(ECM)
Mass Air Flow Injection Timing High Pressure The information exchange between the two control
Others Injection Quantity Pump Solenoid Valve modules takes place via two means.
Response Signal Control Fuel Injection
Additional Signal Unit (Mechanical) • Via analogue signal leads
(PSG)
• Via the CAN-bus
Additional Operations Timing Device
To Timing Control Valve (TCV) The analogue signal leads are used to exchange the
following information.

• Engine speed signal (ECM terminal 91)

• Pump Speed (ECM terminal 105)

• Fuel Cutoff solenoid valve signal (MAB signal) (ECM
terminal 105)

The engine speed signal is sent from the ECM to PSG
based on the input from the crank shaft position (CKP)
sensor.
The analogue CKP sensor signal is converted by the
ECM into a square wave signal.
The fuel cutoff solenoid valve signal is also referred to
as MAB signal.
MAB in this case, refers to the German abbreviation
Magnet ventil ABschaltung that stands for high pressure
solenoid valve cut off.
The MAB signal wire is used for two purposes.
-As a reference for the engine control module (ECM) for
the pump speed (back up for the CKP sensor).
-To turn Off the engine.

The radial plunger distributor type injection pump uses
two control modules to execute full control of the engine

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–65

The following signals are exchanged via the CAN-bus: Characteristic of IAT Sensor -Reference-
From ECM to PSG
100000
• Desired injection quantity

• Desired injection timing

• Engine speed

From PSG to ECM Resistance (ohm) (Solid Line) 10000
• Fuel temperature
• Pump speed 1000
• Cylinder identifier
• Control pulse (actual injection quantity + actual 100

injection timing) 10 10 20 30 40 50 60 70 80 90 100 110
• PSG status -30 -20 -10 0 Intake Air Temp. (deg. C) (Tech2 Reading)

Mass Air Flow (MAF) Sensor & Intake Air
Temperature (IAT) Sensor

The IAT sensor is a thermistor. A temperature changes
the resistance value. And it changes voltage. In other
words it measures a temperature value. Low air
temperature produces a high resistance.
The ECM supplies 5 volts signal to the IAT sensor
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the air temperature
is cold, and it will be low when the air temperature is
hot.

12

(1) Air Cleaner Case
(2) Mass Air Flow (MAF) & Intake Air Temperature

(IAT) Sensor

The mass air flow (MAF) sensor is part of the intake air
system.
It is fitted between the air cleaner and turbocharger and
measure the mass air flowing into the engine.
The mass air flow (MAF) sensor uses a hot film element
to determine the amount of air flowing into the engine.
The mass air flow (MAF) sensor assembly consist of a
mass air flow (MAF) sensor element and an intake air
temperature sensor that are both exposed to the air flow
to be measured.
The mass air flow (MAF) sensor element measures the
partial air mass through a measurement duct on the
sensor housing.
Using calibration, there is an extrapolation to the entire
mass air flow to the engine.

6E–66 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

Throttle Position Sensor (TPS) Crankshaft Position (CKP) Sensor

12 12

(1) Throttle Position Sensor (TPS) (1) Crankshaft Position (CKP) Sensor
(2) Idle Switch (2) Fly wheel with sensor slot
The CKP sensor is located on top of the flywheel
Characteristic of TPS -Reference- housing of the flywheel and fixed with a bolt.
4.5 The CKP sensor is of the magnet coil type. The
4 inductive pickup sensors four gaps in the flywheel
3.5 exciter ring and is used to determine the engine speed
3 and engine cylinder top dead center (TDC).
2.5
Output Voltage (V) 2
1.5
1
0.5
0

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Pedal Position (%) (Tech2 Reading

The TPS is a potentiometer connected to throttle shaft
on the throttle body. It is installed to the main TPS and
idle switch.
The engine control module (ECM) monitors the voltage
on the signal line and calculates throttle position. As the
throttle valve angle is changed when accelerator pedal
moved. The TPS signal also changed at a moved
throttle valve. As the throttle valve opens, the output

increases so that the output voltage should be high.
The engine control module (ECM) calculates fuel
delivery based on throttle valve angle.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–67

Engine Coolant Temperature (ECT) Sensor Vehicle Speed Sensor (VSS)

21 M/T & A/T 4WD

(1) Engine Coolant Temperature (ECT) Sensor
(2) Thermo Unit for Water Temperature Gauge

Characteristic of ECT Sensor -Reference-

100000

10000

Resistance (ohm) (Solid Line) 1000

100

10 10 20 30 40 50 60 70 80 90 100 110 120 130
-30 -20 -10 0 Engine Coolant Temp (deg. C) (Tech2 Reading)

The ECT sensor is a thermistor. A temperature changes A/T 2WD
the resistance value. And it changes voltage. In other
words it measures a temperature value. It is installed on The VSS is a magnet rotated by the transmission output
the coolant stream. Low coolant temperature produces shaft. The VSS uses a hall element. It interacts with the
a high resistance. magnetic field treated by the rotating magnet. It outputs
The ECM supplies 5 volts signal to the ECT sensor pulse signal. The 12 volts operating supply from the
through resisters in the ECM and measures the voltage. meter fuse.
The signal voltage will be high when the engine The engine control module (ECM) calculates the vehicle
temperature is cold, and it will be low when the engine speed by VSS.
The 2WD model fitted with automatic transmission,
temperature is hot. vehicle speed sensor signal is transmitted to from the
TCM to the ECM via vehicle speed meter.

6E–68 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR EGR
(EXHAUST GAS RE-CIRCULATION)

4 56

(1) EGR Valve (1) To EGR Valve
(2) EGR Cooler (Euro 3) / EGR Pipe (Except Euro (2) From Vacuum Pump
(3) EGR EVRV
3) (4) EGR Cooler
(3) Intercooler (5) Thermo Valve
(4) Intake Manifold (6) EGR Valve
(5) Exhaust Manifold
(6) Waste Gate The 4JA1-TC & 4JH1-TC engine with Euro 3 regulation
(7) Fresh Air is equipped with the EGR cooler. The EGR cooler
(8) Exhaust Gas reduces the temperature of the air being drawn into the
(9) Turbocharger engine and the combustion temperature. This results in
reducing nitrogen oxide (Nox) emissions. The 4JH1-TC
engine except Euro 3 regulation, it does not have EGR
cooler. It has steel EGR pipe instead of the cooler.
The amount of EGR is controlled by EVRV (electrical
vacuum regulating valve) via the engine control module
(ECM) command signal depends on the following
inputs.

• Engine speed

• Injection quantity

• Mass air flow

• Intake air temperature

• Coolant temperature

• Barometric pressure

12 3

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–69

7.1ms

Time

0.7ms
Off duty 10% =EGR Pulse Ratio 10%

7.1ms

Time

6.4ms
Off duty 90% =EGR Pulse Ratio 90%

The EVRV is shaped to control vacuum applied to the
diaphragm chamber of the EGR valve based on duty
signal sent from the ECM. The duty ratio is the time that
the EVRV is opened to one cooperate EVRV operating
cycle. A duty ratio change of 90% to 10 % is EGR
amount control.

6E–70 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

GENERAL DESCRIPTION FOR INJECTION Cross-section View
PUMP

Outline

(1) Drive Shaft (1) Drive Shaft
(2) Feed Pump (2) Feed Pump
(3) Pump Camshaft Speed Sensor (3) Pump Camshaft Speed Sensor
(4) Pump Control Unit (PSG) (4) Pump Control Unit (PSG)
(5) Distributor Head (5) Distributor Head
(6) Constant Pressure Valve (CPV) Holder (6) Constant Pressure Valve (CPV) Holder
(7) High Pressure Solenoid Valve (7) High Pressure Solenoid Valve
(8) Constant Pressure Valve (CPV) (8) Constant Pressure Valve (CPV)
(9) Timing Control Valve (TCV) (9) Timing Control Valve (TCV)
(10) Timer (10) Timer
(11) Radial Plunger High Pressure Pump (11) Radial Plunger High Pressure Pump

Instead of the previous face cam type, the radial plunger
distributor type injection pump utilizes a cam ring to
enable fuel injection at high-pressures, marking it
suitable for small, high-speed direct injection diesel
engines. This pump was developed to provide the most
suitable fuel injection quantity and injection timing to
satisfy the demand for engine reliability, driveability, low
smoke, low noise, high output and clear exhaust
emissions.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–71
Low Pressure Fuel Circuit

(1) Rotor Shaft (1) Fuel Suction
(2) Radial Plunger (2) Regulating Valve
(3) High Pressure Passage (3) Overflow Valve
(4) Low Pressure Inlet (4) Feed Pump
(5) Distributor Slit (5) To Fuel Tank
(6) Valve Needle
(7) Barrel The low pressure fuel circuit must supply sufficient fuel
(8) Annular Passage to the high pressure fuel circuit. The main components
(9) Fuel Return are the feed pump, the regulating valve and the
(10) High Pressure Solenoid Valve overflow valve.
(11) High Pressure Outlet
(12) Diaphram Chamber
(13) Accumulator Diaphram

6E–72 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

High Pressure Fuel Circuit Pump Camshaft Speed Sensor

(1) Pump Control Unit (PSG) (1) Pump Camshaft Speed Sensor
(2) Distributor Head (2) Sensor Wheel
(3) High Pressure Solenoid Valve (3) Pump Camshaft Speed Sensor Retaining Ring
(4) Constant Pressure Valve (CPV) (4) Flexible Connector Harness
(5) Radial Plunger High Pressure Pump (5) Drive Shaft

In addition high pressure generating device, the high When the drive shaft rotates, the pump camshaft speed
pressure circuit also consists of fuel piping, and devices sensor receives signal form the sensor wheel, and an
to set the beginning of injection and fuel injection electric pulse is sent through the flexible connecting
quantity. harness to the pump control unit (PSG).
From these signals the pump control unit (PSG) can
The main components are as follows. determine the average pump speed and the momentary
• High pressure generation: Radial Plunger High pump speed.
The pump camshaft speed sensor is mounted to the
Pressure Pump cam ring. Thus, the relationship between the cam ring
• Fuel distribution: Distributor Head and the pump camshaft speed sensor signal is
• Beginning of injection timing: Timing Device constant.
• Prevention of secondary injection: Constant Pressure

Valve (CPV)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–73

The pump camshaft speed sensor signal is utilized for High Pressure Solenoid Valve
the following purposes.
To determine the momentary angular position of the
cam ring.
To calculate the actual speed of the fuel injection pump.

To determine the actual timing plunger position.

Sensor Pump Pump -Cam Ring Angle
Wheel Camshaft Control -Pump Speed
-Timer Position
Speed Unit
Sensor (PSG)

The pump camshaft sensor signal has a tooth gap, and (1) Valve Needle
the crankshaft position (CKP) sensor on the flywheel (2) Magnet Anchor
housing is used as a reference signal of engine top (3) Coil
dead center (TDC) for the start timing of fuel delivery or (4) High Pressure Passage
injection which is to be set.
Fuel injection quantity control is performed from the
beginning of pressure delivery at the beginning of cam
lift until the high pressure solenoid valve opens at the
end of pressure delivery.
This interval is called the pressure delivery interval.
Accordingly, the interval that the high pressure solenoid
valve is closed determines the fuel injection quantity
(high pressure fuel supply ends when the high pressure
solenoid valve opens).

6E–74 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

When current from the pump control unit (PSG) flows to Timing Control Valve (TCV)
the high pressure solenoid valve coil, the magnet
anchor (a movable iron core) pushes the valve needle,
toward the valve seat.
When the valve seat is completely closed by the valve

needle, the way, of the fuel in the high pressure
passage to the low pressure circuit is closed.
The pressure of the fuel in the high pressure passage is
rapidly increased by radial plunger lift, and the high
pressure fuel is delivered through the constant pressure
valve (CPV) to the nozzle holder assembly and is
injected into the engine cylinder.

(1) Valve Needle (1) Cam Ring
(2) Coil (2) Servo Valve
(3) Timer Piston
When the fuel injection quantity demanded by the (4) Outlet
engine is reached, the current to the coil is cut and the (5) Feed Pump
valve needle re-opens the valve seat. (6) Inlet
As a result of this, a path is opened for the fuel in the (7) Fuel Suction
high pressure passage to the low pressure circuit and (8) Ball Pin
the pressure decreases. With a decrease in injection (9) Annular Chamber
pressure the nozzle closes and injection ends. (10) Hydraulic Stopper
(11) Return Passage
(12) Timing Control Valve (TCV)

The pressure of the fuel fed from the feed pump is
adjusted in accordance with speed by the regulating
valve. This delivery pressure acts on the hydraulic
stopper's annular chamber as control pressure.
The chamber pressure of the annular chamber is
controlled by the timing control valve (TCV).
The timing plunger is connected to the cam ring by a
ball pin. Axial movement of the timing plunger is
transferred to the cam ring in the form of rotational
movement. Movement to the right of the timing plunger
(to the spring side) advances injection timing.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–75

Engine Load Engine Pump Timing
Engine Speed Control Control Control
Engine Coolant Module Valve
Temperature (ECM) Unit (TCV)
(PSG)

Pump Camshaft
Speed Sensor

(1) Coil The engine control module (ECM) contains
(2) From Annular Chamber characteristic maps of the start of injection,
(3) To Feed Pump corresponding to engine operating conditions (engine
(4) Orifice load, engine speed and engine coolant temperature).
(5) Valve Needle The pump control unit (PSG) is constantly comparing
the set start of injection timing and the actual start of
When control current flows to the timing control valve injection timing. If there is a difference, the timing
(TCV) coil, the valve needle opens and the fuel annular control valve (TCV) is controlled by the duty ratio. (The
chamber flows through the orifice to the feed pump inlet. actual start of injection timing is determined from the
Consequently, the pressure of the annular chamber pump camshaft speed sensor.)
decreases and the hydraulic stopper is moved to the
retard side.

The timing control valve (TCV) acts as a variable
throttle, using the rapid opening and closing (cycling) of
the valve needle in the timing control valve (TCV).
At normal operation, the TCV controls the pressure
acting on the annular chamber so that the hydraulic
stopper cam move to any position, from the retard
position to the advance position. At this time, the duty
ratio is set by the pump control unit (PSG).
Duty ratio is the ratio of the time that the timing control
valve (TCV) is opened to one complete timing control
valve (TCV) operating cycle. A duty ratio change of
100% to 0% is an advance in injection timing. (The
VP44 displays an ON duty ratio.)

6E–76 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

ISUZU Strategy Based Diagnostics

Overview You have maximum efficiency in diagnosis when you
have an effective, organized plan for your work.
As a retail service technician, you are part of the ISUZU Strategy Based Diagnostics (refer to Figure 1) provides
service team. The team goal is FIX IT RIGHT THE you with guidance as you create and follow a plan of
FIRST TIME for the satisfaction of every customer. You action for each specific diagnostic situation.
are a very important member of the team as you
diagnose and repair customer vehicles.

STRATEGY BASED DIAGNOSTICS CHART

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–77

Diagnostic Thought Process • Circuit testing tools
• Vehicle road tests
As you follow a diagnostic plan, every box on the • Complaint check sheet
Strategy Based Diagnostics chart requires you to use • Contact with the customer
the diagnostic thought process. This method of thinking
optimizes your diagnosis in the following ways: 2. Perform Preliminary Checks
• Improves your understanding and definition of the
NOTE: An estimated 10 percent of successful vehicle
customer complaint repairs are diagnosed with this step!
• Saves time by avoiding testing and/or replacing good
What you should do
parts
• Allows you to look at the problem from different You perform preliminary checks for several reasons:
• To detect if the cause of the complaint is VISUALLY
perspectives
• Guides you to determine what level of understanding OBVIOUS
• To identify parts of the system that work correctly
about system operation is needed: • To accumulate enough data to correctly and
– Owner’s manual level
– Service manual level accurately search for a ISUZU Service Bulletin on
– In-depth (engineering) level ISUZU Web site.
The initial checks may vary depending on the
– Owner’s manual level complexity of the system and may include the following
– Service manual level actions:
– In-depth (engineering) level • Operate the suspect system
• Make a visual inspection of harness routing and
1. Verify the Complaint accessible/visible power and ground circuits
• Check for blown fuses
What you should do • Make a visual inspection for separated connectors
• Make a visual inspection of connectors (includes
To verify the customer complaint, you need to know the checking terminals for damage and tightness)
correct (normal) operating behavior of the system and • Check for any DTCs stored by the on-board
verify that the customer complaint is a valid failure of the computers
system. • Sense unusual noises, smells, vibrations or
The following information will help you verify the movements
complaint: • Investigate the vehicle service history (call other
• WHAT the vehicle model/options are dealerships, if appropriate)
• WHAT aftermarket and dealer-installed accessories
What resources you should use
exist
• WHAT related system(s) operate properly Whenever appropriate, you should use the following
• WHEN the problem occurs resources for assistance in performing preliminary
• WHERE the problem occurs checks:
• HOW the problem occurs • Tech II or other technical equipment for viewing DTCs
• HOW LONG the condition has existed (and if the • Service manual information:

system ever worked correctly) – Component locations
• HOW OFTEN the problem occurs – Harness routing
• Whether the severity of the problem has increased, – Wiring schematics
– Procedures for viewing DTCs
decreased or stayed the same • Dealership service history file
• Vehicle road test
What resources you should use • Identical vehicle or system for comparison

Whenever possible, you should use the following
resources to assist you in verifying the complaint:
• Service manual Theory or Circuit Description

sections
• Service manual “System Performance Check”
• Owner manual operational description
• Technician experience
• Identical vehicle for comparison

6E–78 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

3. Check Bulletins and to the customer complaint.
Troubleshooting Hints
What resources you should use
NOTE: As estimated 30 percent of successful vehicle
repairs are diagnosed with this step! Whenever appropriate, you should use the following
resources to perform service manual diagnostic
What you should do procedures:

You should have enough information gained from • Service manual
preliminary checks to accurately search for a bulletin • Technical equipment (for analyzing diagnostic data)
and other related service information. Some service
manual sections provide troubleshooting hints that • Digital multimeter and circuit testing tools
match symptoms with specific complaints.
• Essential and special tools
What resources you should use
5c. Technician Self Diagnoses
You should use the following resources for assistance in
checking for bulletins and troubleshooting hints: When there is no DTC stored and no matching
• Printed bulletins symptom for the condition identified in the service
• Access ISUZU Bulletin Web site. manual, you must begin with a thorough understanding
• Videotapes of how the system(s) operates. Efficient use of the
• Service manual service manual combined with you experience and a
good process of elimination will result in accurate
4. Perform Service Manual diagnosis of the condition.
Diagnostic Checks
What you should do
What you should do
Step 1: Identify and understand the suspect
The “System Checks” in most service manual sections circuit(s)
and in most cells of section 8A (electrical) provide you
with: Having completed steps 1 through 4 of the Strategy
• A systematic approach to narrowing down the Based Diagnostics chart, you should have enough
information to identify the system(s) or sub-system(s)
possible causes of a system fault involved. Using the service manual, you should
• Direction to specific diagnostic procedures in the determine and investigate the following circuit
characteristics:
service manual
• Assistance to identify what systems work correctly • Electrical:

What resources you should use – How is the circuit powered (power distribution
charts and/or fuse block details)?
Whenever possible, you should use the following
resources to perform service manual checks: – How is the circuit grounded (ground distribution
• Service manual charts)?
• Technical equipment (for viewing DTCs and
– How is the circuit controlled or sensed (theory of
analyzing data) operation):
• Digital multimeter and circuit testing tools – If it is a switched circuit, is it normally open or
• Other tools as needed normally closed?

5a and 5b. Perform Service Manual – Is the power switched or is the ground
Diagnostic Procedures switched?

NOTE: An estimated 40 percent of successful vehicle – Is it a variable resistance circuit (ECT sensor
repairs are diagnosed with these steps! or TP sensor, for example)?

What you should do – Is it a signal generating device (MAF sensor of
VSS, for example)?
When directed by service manual diagnostic checks,
you must then carefully and accurately perform the – Does it rely on some mechanical/vacuum
steps of diagnostic procedures to locate the fault related device to operate?

• Physical:

– Where are the circuit components (component
locators and wire harness routing diagrams):

– Are there areas where wires could be chafed
or pinched (brackets or frames)?

– Are there areas subjected to extreme
temperatures?

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–79

– Are there areas subjected to vibration or at the component
movement (engine, transmission or
suspension)? • If a number of components do no operate, begin tests
at the area of commonality (such as power sources,
– Are there areas exposed to moisture, road salt ground circuits, switches or major connectors)
or other corrosives (battery acid, oil or other
fluids)? What resources you should use

– Are there common mounting areas with other Whenever appropriate, you should use the following
systems/components? resources to assist in the diagnostic process:
• Service manual
– Have previous repairs been performed to wiring, • Technical equipment (for data analysis)
connectors, components or mounting areas • Experience
(causing pinched wires between panels and • Technical Assistance
drivetrain or suspension components without • Circuit testing tools
causing and immediate problem)?
5d. Intermittent Diagnosis
– Does the vehicle have aftermarket or dealer-
installed equipment (radios, telephone, etc.) By definition, an intermittent problem is one that does
not occur continuously and will occur when certain
Step 2: Isolate the problem conditions are met. All these conditions, however, may
not be obvious or currently known. Generally,
At this point, you should have a good idea of what could intermittents are caused by:
cause the present condition, as well as could not cause
the condition. Actions to take include the following: • Faulty electrical connections and wiring

• Divide (and separate, where possible) the system or • Malfunctioning components (such as sticking relays,
circuit into smaller sections solenoids, etc.)

• Confine the problem to a smaller area of the vehicle • EMI/RFI (Electromagnetic/radio frequency
(start with main harness connections while removing
panels and trim as necessary in order to eliminate interference)
large vehicle sections from further investigation)
• Aftermarket equipment
• For two or more circuits that do not share a common Intermittent diagnosis requires careful analysis of
power or ground, concentrate on areas where suspected systems to help prevent replacing good
harnesses are routed together or connectors are parts. This may involve using creativity and ingenuity to
shared (refer to the following hints) interpret customer complaints and simulating all
external and internal system conditions to duplicate the
Hints problem.

Though the symptoms may vary, basic electrical failures What you should do
are generally caused by:
Step 1: Acquire information
• Loose connections:
A thorough and comprehensive customer check sheet
– Open/high resistance in terminals, splices, is critical to intermittent problem diagnosis. You should
connectors or grounds require this, since it will dictate the diagnostic starting
point. The vehicle service history file is another
• Incorrect connector/harness routing (usually in new source for accumulating information about the
vehicles or after a repair has been made): complaint.

– Open/high resistance in terminals, splices, Step 2: Analyze the intermittent problem
connectors of grounds
Analyze the customer check sheet and service history
• Corrosion and wire damage: file to determine conditions relevant to the suspect
system(s).
– Open/high resistance in terminals, splices, Using service manual information, you must identify,
connectors of grounds trace and locate all electrical circuits related to the
malfunctioning system(s). If there is more than one
• Component failure: system failure, you should identify, trace and locate
areas of commonality shared by the suspect circuits.
– Opens/short and high resistance in relays,
modules, switches or loads

• Aftermarket equipment affecting normal operation of
other systems

You may isolate circuits by:

• Unplugging connectors or removing a fuse to
separate one part of the circuit from another part

• Operating shared circuits and eliminating those that
function normally from the suspect circuit

• If only one component fails to operate, begin testing

6E–80 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

Step 3: Simulate the symptom and isolate the For parts and sensors, apply slight vibration to the part
problem with a light tap of the finger while monitoring the system
for a malfunction.
Simulate the symptom and isolate the system by
reproducing all possible conditions suggested in Step 1 2. Heat
while monitoring suspected circuits/components/
systems to isolate the problem symptom. Begin with the This method is important when the complaint suggests
most logical circuit/component. that the problem occurs in a heated environment. Apply
Isolate the circuit by dividing the suspect system into moderate heat to the component with a hair drier or
simpler circuits. Next, confine the problem into a smaller similar tool while monitoring the system for a
area of the system. Begin at the most logical point (or malfunction.
point of easiest access) and thoroughly check the CAUTION: Care must be take to avoid overheating
isolated circuit for the fault, using basic circuit tests. the component.

Hints 3. Water and Moisture
You can isolate a circuit by:
This method may be used when the complaint suggests
• Unplugging connectors or removing a fuse to that the malfunction occurs on a rainy day or under
separate one part of the circuit from another conditions of high humidity. In this case, apply water in a
light spray on the vehicle to duplicate the problem.
• If only component fails to operate, begin testing the CAUTION: Care must be take to avoid directly
component exposing electrical connections to water.

• If a number of components do not operate, begin test 4. Electrical loads
at areas of commonality (such as power sources,
ground circuits, switches, main connectors or major This method involves turning systems ON (such as the
components) blower, lights or rear window defogger) to create a load
on the vehicle electrical system at the same time you
• Substitute a known good part from the parts are monitoring the suspect circuit/component.
department or the vehicle system
5e. Vehicle Operates as Designed
• Try the suspect part in a known good vehicle
See Symptom Simulation Tests on the next page for This condition refers to instances where a system
problem simulation procedures. Refer to service manual operating as designed is perceived to be unsatisfactory
sections 6E and 8A for information about intermittent or undesirable. In general, this is due to:
diagnosis. Follow procedures for basic circuit testing in
service manual section 8A. • A lack of understanding by the customer

What resources you should use • A conflict between customer expectations and
vehicle design intent
Whenever appropriate, you should use the following
resources to assist in the diagnostic process: • A system performance that is unacceptable to the
• Service manual customer

• Bulletins What you should do

• Digital multimeter (with a MIN/MAX feature) You can verify that a system is operating as designed
by:
• Tech II and Tech II upload function
• Reviewing service manual functional/diagnostic
• Circuit testing tools (including connector kits/ checks
harnesses and jumper wires)
• Examining bulletins and other service information for
• Experience supplementary information
• Intermittent problem solving simulation methods
• Compare system operation to an identical vehicle
• Customer complaint check sheet If the condition is due to a customer misunderstanding
or a conflict between customer expectation and system
Symptom Simulation Tests operation, you should explain the system operation to
the customer.
1. Vibration If the complaint is due to a case of unsatisfactory
system performance, you should contact Technical
This method is useful when the customer complaint Assistance for the latest information.
analysis indicates that the problem occurs when the
vehicle/system undergoes some form of vibration. What resources you should use
For connectors and wire harness, slightly shake
vertically and horizontally. Inspect the connector joint Whenever possible, you should use the following
and body for damage. Also, tapping lightly along a resources to facilitate the diagnostic process:
suspected circuit may be helpful.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–81

• Vehicle service information (service manual, etc.)
• ISUZU field support
• Experience
• Identical vehicle or system for comparison

6. Re-examine the complaint

When you do not successfully find/isolate the problem
after executing a diagnostic path, you should re-
examine the complaint.

What you should do

In this case, you will need to backtrack and review
information accumulated from step 1 through 4 of
Strategy Based Diagnostics. You also should repeat any
procedures that require additional attention.
A previous path may be eliminated from consideration
only if you are certain that all steps were executed as
directed. You must then select another diagnostic path
(step 5a, 5b, 5c or 5d). If all possible options have been
explored, you may call or seek ISUZU field support.

What resources you should use

Whenever possible, you should use the following
resources to facilitate the diagnostic process:
• Service manual
• Accumulated information form a previous diagnostic

path
• Service information and publications
• ISUZU field support

7. Repair and Verify Fix

What you should do

After you have located the cause of the problem, you
must execute a repair by following recommended
service manual procedures.
When the repair is completed, you should verify the fix
by performing the system checks under the conditions
listed in the customer complaint.
If applicable, you should carry out preventive measures
to avoid a repeat complaint.

What resources you should use

Whenever possible, you should use the following
resources to facilitate the repair process:
• Electrical repair procedures
• Service manual information and publications

6E–82 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

GENERAL SERVICE INFORMATION ON-BOARD DIAGNOSTIC (OBD)

Serviceability Issues On-Board Diagnostic (Self Diagnosis
System) Tests
Non-OEM Parts
A diagnostic test is a series of steps, the result of which
All of the OBD diagnostics have been calibrated to run is a pass or fail reported to the diagnostic executive.
with OEM parts. Accordingly, if commercially sold When a diagnostic test reports a pass result, the
sensor or switch is installed, it makes a wrong diagnosis diagnostic executive records the following data:
and turns on the check engine lamp.
Aftermarket electronics, such as cellular phones, • The diagnostic test has been completed since the
stereos, and anti-theft devices, may radiate EMI into the last ignition cycle.
control system if they are improperly installed. This may
cause a false sensor reading and turn on the check • The diagnostic test has passed during the current
engine lamp. ignition cycle.

Poor Vehicle Maintenance • The fault identified by the diagnostic test is not
currently active.
The sensitivity of OBD diagnostics will cause the check
engine lamp to turn on if the vehicle is not maintained When a diagnostic test reports a fail result, the
properly. Restricted oil filters, fuel filters, and crankcase diagnostic executive records the following data:
deposits due to lack of oil changes or improper oil
viscosity can trigger actual vehicle faults that were not • The diagnostic test has been completed since the
previously monitored prior to OBD. Poor vehicle last ignition cycle.
maintenance can not be classified as a “non-vehicle
fault”, but with the sensitivity of OBD diagnostics, • The fault identified by the diagnostic test is currently
vehicle maintenance schedules must be more closely active.
followed.
• The fault has been active during this ignition cycle.
Related System Faults
• The operating conditions at the time of the failure.
Many of the OBD system diagnostics will not run if the
ECM detects a fault on a related system or component. The Diagnostic Executive

Visual/Physical Engine Compartment The Diagnostic Executive is a unique segment of
Inspection software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
Perform a careful visual and physical engine for recording and displaying their results. The main
compartment inspection when performing any responsibilities of the Diagnostic Executive are listed as
diagnostic procedure or diagnosing the cause of an follows:
emission test failure. This can often lead to repairing a
problem without further steps. Use the following • Commanding the check engine lamp on and off
guidelines when performing a visual/physical
inspection: • DTC logging and clearing

• Inspect all vacuum hoses for punches, cuts, • Current status information on each diagnostic
disconnects, and correct routing.
Diagnostic Information
• Inspect hoses that are difficult to see behind other
components. The diagnostic charts and functional checks are
designed to locate a faulty circuit or component through
• Inspect all wires in the engine compartment for a process of logical decisions. The charts are prepared
proper connections, burned or chafed spots, pinched with the requirement that the vehicle functioned
wires, contact with sharp edges or contact with hot correctly at the time of assembly and that there are not
exhaust manifolds or pipes. multiple faults present.
There is a continuous self-diagnosis on certain control
Basic Knowledge of Tools Required functions. This diagnostic capability is complemented
by the diagnostic procedures contained in this manual.
NOTE: Lack of basic knowledge of this powertrain The language of communicating the source of the
when performing diagnostic procedures could result in malfunction is a system of diagnostic trouble codes.
an incorrect diagnosis or damage to powertrain When a malfunction is detected by the control module, a
components. Do not attempt to diagnose a powertrain diagnostic trouble code is set and the check engine
problem without this basic knowledge. lamp is illuminated.
A basic understanding of hand tools is necessary to
effectively use this section of the Service Manual. Check Engine Lamp

The check engine lamp looks the same as the check
engine lamp you are already familiar with, the “Check
Engine” lamp.
Basically, the check engine lamp is turned on when the

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–83

ECM detects a DTC that will impact the vehicle Reading Flash Diagnostic Trouble Codes
emissions.
The provision for communicating with the Engine
• When the check engine lamp remains “ON” while the Control Module (ECM) is the Data Link Connector
engine is running, or when a malfunction is (DLC). The DLC is located in the front console box. It is
suspected due to a driveability or emissions problem, used in the assembly plant to receive information in
a Powertrain On-Board Diagnostic (OBD) System checking that the engine is operating properly before it
Check must be performed. The procedures for these leaves the plant.
checks are given in On-Board Diagnostic (OBD) The diagnostic trouble code(s) (DTCs) stored in the
System Check. These checks will expose faults ECM’s memory can be read either through a hand-held
which may not be detected if other diagnostics are diagnostic scanner plugged into the DLC or by counting
performed first. the number of flashes of the check engine lamp when
the diagnostic test terminal of the DLC is grounded. The
Data Link Connector (DLC) DLC terminal “6” (diagnostic request) is pulled “Low”
(grounded) by jumping to DLC terminal “4 or 5”, which is
The provision for communication with the contorl a ground wire.
module is the Data Link Connector (DLC). It is located This will signal the ECM that you want to “flash” DTC(s),
behind the lower front instrument panel. The DLC is if any are present. Once terminals “4 or 5” and “6” have
used to connect to a Tech2. Some common uses of the been connected, the ignition switch must be moved to
Tech2 are listed below: the “ON” position, with the engine not running.
The check engine lamp will indicate a DTC three times if
• Identifying stored Diagnostic Trouble Codes (DTCs). a DTC is present. If more than one DTC has been
stored in the ECM’s memory, the DTC(s) will be output
• Clearing DTCs. from the lowest to the highest, with each DTC being
displayed three times.
• Reading serial data. The DTC display will continue as long as the DLC is
shorted.

Reading Diagnostic Trouble Codes Using a
Tech 2

The procedure for reading diagnostic trouble code(s) is
to used a diagnostic Tech2. When reading DTC(s),
follow instructions supplied by Tech2 manufacturer.
For the 1998 model year, Isuzu dealer service
departments will continue to use Tech2.

Verifying Vehicle Repair Clearing Diagnostic Trouble Codes
To clear Diagnostic Trouble Codes (DTCs), use the
Verification of vehicle repair will be more Tech2 “clear DTCs” or “clear information” function.
comprehensive for vehicles with OBD system When clearing DTCs follow instructions supplied by the
diagnostic. Following a repair, the technician should Tech2 manufacturer.
perform the following steps:
History DTC
1. Review and record the Fail Records for the DTC
which has been diagnosed. History DTC can be candeled after 40 cycle driving with
no defect. Or history code can be deleted by Tech 2
2. Clear DTC(s). “Clear DTCs” function.

3. Operate the vehicle within conditions noted in the
Fail Records.

4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.

Following these steps is very important in verifying
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.

6E–84 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–85

DIAGNOSIS WITH Tech 2 • Connect the SAE 16/19 adapter (3) to the DLC
cable (4).
If no codes are set:
• Refer to F1: Data Display and identify the electrical • Connect the DLC cable (4) to the Tech 2 (5).

faults that are not indicated by trouble code. • Connect the SAE 16/19 adapter (3) to the data
• Refer to “SYMPTOM DIAGNOSIS”. link connector of the vehicle.

If codes are set:

1. Record all trouble codes displayed by Tech 2 and
check id the codes are intermittent.

2. Clear the codes.

3. Drive the vehicle for a test to reproduce the faulty
status.

4. Check trouble codes again using the Tech 2.

5. If no codes is displayed by test driving, the fault is
intermittent. In this case, refer to “DIAGNOSIS
AIDS”.

6. If a code is present, refer to DTC Chart for
diagnosis.

7. Check trouble codes again using the Tech 2.

Tech 2 CONNECTION

• Turn the key switch of the vehicle ON and press
the “PWR” key of the Tech 2.

• Check the display of the Tech 2.

NOTE: Be sure to check that the power is not supplied
to the Tech 2 when attaching or removing the PCMCIA
card.

Tech 2 scan tool is used to electrically diagnose the
automatic transmission system and to check the
system. The Tech 2 enhances the diagnosis efficiency
though all the troubleshooting can be done without the
Tech 2.

1. Configuration of Tech 2

• Tech 2 scan tool kit (No. 7000086), Tech 2 scan
tool (No. 7000057) and DLC cable (No.
3000095).

• SAE 16/19 adapter (No. 3000098) (3), RS232
loop back connector (No. 3000112) (2) and
PCMCIA card (No. 3000117) (1).

2. Tech 2 Connection

• Check the key switch is turn OFF.

• Insert the PCMCIA card (1) into the Tech 2 (5).

6E–86 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
TECH 2 OPERATING FLOW CART (START UP)

Vehicle Identification
(UB) Trooper, Bighorn
(UE) Rodeo,/Amigo, Wizard/Mu
(TF/UC) LUV, Frontier, LAO-Rodeo
(TBR)
(N*) ELF, NPR, NQR

Press (ENTER) to Continue

Press “ENTER” key. Select “(TF/UC)”.

Main Menu System Selection Menu
F0: Diagnostic F0: Powertrain
F1: Service Programming System (SPS) F1: Chassis
F2: View Capture Data F3: Body
F3: Tool Option
F4: Download/ Upload Help

Select “F0: Diagnostic”. Select “F0: Powertrain”.

Vehicle Identification Vehicle Identification
(3) 2003 4JH1-TC Bosch
(2) 2002 4JA1-TC Bosch
(1) 2001 4JH1-T Denso
(Y) 2000 3.5L V6 6VE1 Hitachi
(X) 1999 AW30-40LE
(W) 1998 A/T JR405E

Select “(3) 2003”or later. Select “4JA1-TC Bosch” or “4JH1-TC Bosch”.

Select “4JA1-TC Bosch” or “4JH1-TC Bosch” in Vehicle Identification menu and the following table is shown in the
Tech 2 screen.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–87

F0: Diagnostic Trouble Codes F1: Data Display
F0: Read DTC Infor As Stored By ECU The purpose of the “Data Display” mode is to
F1: Clear DTC Information continuously monitor data parameters.
The current actual values of all important sensors and
F1: Data Display signals in the system are display through F1 mode.
See the “Typical Scan Data” section.
F2: Snapshot
F2: Snapshot
F3: Miscellaneous Test “Snapshot” allows you to focus on making the condition
F0: Lamps occur, rather than trying to view all of the data in
F0: Glow Time Telltale Test anticipation of the fault.
F1: Relays The snapshot will collect parameter information around
F0: Glow Time Relay Test a trigger point that you select.
F2: Solenoids
F0: EGR Solenoid Test F3: Miscellaneous Test:
F3: Engine Speed (RPM) Control The purpose of “Miscellaneous Test” mode is to check
for correct operation of electronic system actuators.
F4: Programming
F0: Program VIN F4: Programming (Factory Use Only)
F1: Lock ECU The purpose of “Programming” is to program VIN in the
ECM and lock the programmed data.

F0: Diagnostic Trouble Code
The purpose of the “Diagnostic Trouble Codes” mode is
to display stored trouble code in the ECM.
When “Clear DTC Information” is selected, a “Clear
DTC Information”, warning screen appears.
This screen informs you that by cleaning DTC's “all
stored DTC information in the ECM will be erased”.
After clearing codes, confirm system operation by test
driving the vehicle.

Symptom Code:

DTC No. Read DTC Infor As Stored By ECU
P0100 Present

(7) Mass Air Flow (MAF) Sensor
Voltage Supply Circuit High Input

Symptom Code

This number or alphabet means identification of the
malfunction. Each DTC includes plural symptoms, such
as DTC P0100 has four kinds of symptom code (7), (9),
(B) and (C). DTC chart (check procedure) is separated
depending on the symptom code.

6E–88 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
TYPICAL SCAN DATA & DEFINITIONS (ENGINE DATA)

4JA1-TC ENGINE

Use the typical values table only after the On-Board Diagnostic System check has been completed, no DTC(s) were
noted, and you have determined that the On-Board Diagnostic are functioning properly.
Tech2 values from a properly running engine may be used for comparison with the engine you are diagnosing.
Condition : Vehicle stopping, engine running, air conditioning off & after warm-up (Coolant temperature approximately
80 deg. C)

Tech 2 Parameter Units Idle 1500rpm 2000rpm Description

1 Engine Speed rpm 730 1475 - 1975 - The engine speed is measured by ECM from the CKP

1525 2025 sensor.

2 Vehicle Speed km/h / MPH 0 0 0 This displays vehicle speed. The vehicle speed is

measured by ECM from the vehicle speed sensor.

3 Pump Speed rpm 345 - 385 725 - 775 975 - 1025 This displays injection pump speed. The injection speed is
measured by ECM from the pump cam sensor.

4 Accelerator Position % 0 4-6 6-8 Throttle position operating angle is measured by the ECM
Sensor Signal
from throttle position output voltage. This should display

0% at idle and 99 - 100% at full throttle.

5 Idle Switch Active/ Active Active Inactive 0V This displays operating status of the idle switch. This
Inactive 0V
should display "Active" until the accelerator position nearly
4 - 5%.

6 Mass Air Flow mg/strk 380 - 420 360 - 400 380 - 420 This displays calculated intake air volume for one cylinder
Sensor stroke. The mass air flow is measured by ECM from the

MAF sensor output voltage.

7 Desired Mass Air mg/strk 350 350 350 - 370 This displays desired intake air volume for one cylinder
Flow stroke. The desired mass air flow is calculated by ECM
depending on engine condition.

8 Barometric Pressure hpa Depends Depends Depends The barometric pressure is measured by ECM from the
on altitude on altitude on altitude sensor in the ECM. This data is changing by altitude.

9 Desired Injection mg/stk 8 - 10 6 - 10 7 - 10 This displays desired value from the ECM. The ECM
Quantity compensates for fuel rate to basic rate.

10 Injection Quantity mg/stk 8 - 10 5 - 10 5-9 This displays calculated actual fuel quantity from the PSG.
The PSG receives desired injection quantity from the ECM.
And, it compensates actual injection depending on timer
position to determine duration of the high pressure
solenoid valve operation.

11 Desired Fuel Injection deg. CA 2-4 2- 5 3-5 This displays desired injection timing from the ECM. The
Start
ECM compensates for fuel injection timing by throttle

position and various sensor signal.

12 Actual Injection Start deg. CA 2-4 2-5 3-5 This displays calculated actual injection timing based on
CKP signal and pump cam signal. The PSG controls TCV

duty ratio to meet desired injection timing from the ECM.

13 Coolant Temperature deg. C / deg. 80 - 85 80 - 85 80 - 85 The ECT is measured by ECM from ECT sensor output
F voltage. This data is changing by coolant temperature.
When the engine is normally warm upped, this data
displays approximately 80 deg. C.

14 Fuel Temperature deg. C / deg. Depends Depends Depends The FT is measured by PSG from FT sensor. This data is
F on fuel on fuel on fuel changing by fuel temperature.

temp. temp. temp.

15 Intake Air deg. C / deg. Depends Depends Depends The IAT is measured by ECM from IAT sensor output
Temperature
F on ambient on ambient on ambient voltage. This data is changing by intake air temperature.

temp. temp. temp.

16 Ignition Status On12V/ On 12V On 12V On 12V This displays the key switch status indicated by the ECM
Off0V
with key switch signal. This should display "Off 0V" at key
OFF and "On12V" at key ON.

17 Brake Switch 1 Active/ Inactive Inactive Inactive This displays operating status of the brake switch. This
Inactive should display "Active" when the brake pedal is stepped

on.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–89

Tech 2 Parameter Units Idle 1500rpm 2000rpm Description

18 Brake Switch 2 Active/ Inactive Inactive Inactive This displays operating status of the brake switch. This
Inactive
should display "Active" when the brake pedal is stepped
on.

19 Clutch Switch Active/ Inactive Inactive Inactive This displays operating status of the clutch switch. This
Inactive should display "Active" when the clutch pedal is stepped

on.

20 Neutral Switch On/Off On On On This displays operating status of the neutral switch. This
should display "On" when the gear position is neutral.

21 A/C Information Active 12V/ Inactive 0V Inactive 0V Inactive 0V This displays the air conditioner request signal. This
Switch
Inactive 0V should display "Active 12V" when the air conditioner switch

is switched on.

22 Diagnostic Request Active 0V/ Inactive Inactive Inactive This displays the diagnostic request signal. This should
12V 12V display "Inactive 12V" when the Tech 2 is connected.
Inactive 12V 12V

23 System Voltage V 10 - 14 10 - 14 10 - 14 This displays the system voltage measured by the ECM at
ignition feed.

24 Main Relay Active/ Active Active Active This displays operating status for the ECM main relay. This
Inactive
should display "Active" when the key switch is turned on
and while engine is running.

25 Glow Time Relay Active 0V/ Inactive Inactive Inactive This displays operating status for the glow relay. This
12V 12V should display "Inactive 12V" when the engine is warm
Inactive12V 12V
upped.

26 Check Engine Light On/Off Off Off Off This displays operating status for the Check Engine Lamp.
This should display "On" when the Check Engine Lamp is
turned on.

27 Glow Time Telltale On/Off Off Off Off This displays operating status for the glow indicator lamp.
This should display "On" when the glow lamp is turned on.

28 Desired Engine Idle rpm 730 730 730 The desired engine idle speed that the ECM commanding.
Speed
The ECM compensates for various engine loads based on
engine coolant temperature.

29 A/C Request Active 0V/ Inactive Inactive Inactive This displays operating status of the A/C compressor. This
12V 12V should display "Active 0V" when the compressor relay is
Inactive 12V 12V
operated.

30 Immobilizer Active/ Inactive Inactive Inactive This should display "Inactive" when the immobilizer is
Inactive correctly operated.

31 Immobilizer Signal Received/ Not Not Not This should display "Not Received" when the immobilizer is
Not Received Received Received not activated.
Received

32 Immobilizer Function Yes/ No Yes Yes Yes This should display "Yes" when the immobilizer is correctly
Programmed programmed.

33 EGR Pulse Ratio % 70 70 70 This displays the duty signal from the ECM to control the
EGR flow amount.
(Exhaust Gas

Recirculation)

6E–90 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
TYPICAL SCAN DATA & DEFINITIONS (ENGINE DATA)

4JH1-TC ENGINE

Use the typical values table only after the On-Board Diagnostic System check has been completed, no DTC(s) were
noted, and you have determined that the On-Board Diagnostic are functioning properly.
Tech2 values from a properly running engine may be used for comparison with the engine you are diagnosing.
Condition : Vehicle stopping, engine running, air conditioning off & after warm-up (Coolant temperature approximately
80 deg. C)

Tech 2 Parameter Units Idle 1500rpm 2000rpm Definition

1 Engine Speed rpm 675 - 725 1475 - 1975 - The engine speed is measured by ECM from the CKP
1525 2025 sensor.

2 Vehicle Speed km/h / MPH 0 0 0 This displays vehicle speed. The vehicle speed is

measured by ECM from the vehicle speed sensor.

3 Pump Speed rpm 335 - 375 725 - 775 975 - 1025 This displays injection pump speed. The injection speed is
measured by ECM from the pump cam sensor.

4 Accelerator Position % 0 3-5 5-7 Throttle position operating angle is measured by the ECM
Sensor Signal
from throttle position output voltage. This should display

0% at idle and 99 - 100% at full throttle.

5 Idle Switch Active/ Active Active/ Inactive 0V This displays operating status of the idle switch. This
Inactive 0V
Inactive 0V should display "Active" until the accelerator position nearly

4 - 5%.

6 Mass Air Flow mg/strk 420 - 490 380 - 460 410 - 480 This displays calculated intake air volume for one cylinder
Sensor stroke. The mass air flow is measured by ECM from the
MAF sensor output voltage.

7 Desired Mass Air mg/strk 430 - 470 380 - 420 410 - 470 This displays desired intake air volume for one cylinder
Flow
stroke. The desired mass air flow is calculated by ECM
depending on engine condition.

8 Barometric Pressure hpa Depends Depends Depends The barometric pressure is measured by ECM from the
on altitude on altitude on altitude sensor in the ECM. This data is changing by altitude.

9 Desired Injection mg/stk 6 - 10 6 - 10 7 - 11 This displays desired value from the ECM. The ECM
Quantity compensates for fuel rate by throttle position and various

sensor signals.

10 Injection Quantity mg/stk 6 - 10 6 - 10 7 - 11 This displays calculated actual fuel quantity from the PSG.
The PSG receives desired injection quantity from the ECM.
And, it compensates actual injection depending on timer
position to determine duration of the high pressure
solenoid valve operation.

11 Desired Fuel Injection deg. CA 1-3 2-4 3-5 This displays desired injection timing from the ECM. The
Start ECM compensates for fuel injection timing by throttle
position and various sensor signal.

12 Actual Injection Start deg. CA 1-3 2-4 3-5 This displays calculated actual injection timing based on

CKP signal and pump cam signal. The PSG controls TCV
duty ratio to meet desired injection timing from the ECM.

13 Coolant Temperature deg. C / deg. 80 - 85 80 - 85 80 - 85 The ECT is measured by ECM from ECT sensor output
F voltage. This data is changing by coolant temperature.
When the engine is normally warm upped, this data
displays approximately 80 deg. C.

14 Fuel Temperature deg. C / deg. Depends Depends Depends The FT is measured by PSG from FT sensor. This data is
F changing by fuel temperature.
on fuel on fuel on fuel
temp. temp. temp.

15 Intake Air deg. C / deg. Depends Depends Depends The IAT is measured by ECM from IAT sensor output
Temperature
F on ambient on ambient on ambient voltage. This data is changing by intake air temperature.

temp. temp. temp.

16 Ignition Status On12V/ On 12V On 12V On 12V This displays the key switch status indicated by the ECM
Off0V with key switch signal. This should display "Off 0V" at key
OFF and "On12V" at key ON.

17 Brake Switch 1 Active/ Inactive Inactive Inactive This displays operating status of the brake switch. This
Inactive
should display "Active" when the brake pedal is stepped
on.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–91

Tech 2 Parameter Units Idle 1500rpm 2000rpm Definition

18 Brake Switch 2 Active/ Inactive Inactive Inactive This displays operating status of the brake switch. This
Inactive should display "Active" when the brake pedal is stepped

on.

19 Clutch Switch (M/T Active/ Inactive Inactive Inactive This displays operating status of the clutch switch. This
should display "Active" when the clutch pedal is stepped
Only) Inactive on.

20 Neutral Switch On/Off On On On This displays operating status of the neutral switch. This

should display "On" when the gear position is neutral (M/T)
or P, N position (A/T).

21 A/C Information Active 12V/ Inactive 0V Inactive 0V Inactive 0V This displays the air conditioner request signal. This
Switch
Inactive 0V should display "Active 12V" when the air conditioner switch

is switched on.

22 Diagnostic Request Active 0V/ Inactive Inactive Inactive This displays the diagnostic request signal. This should
12V 12V display "Inactive 12V" when the Tech 2 is connected.
Inactive 12V 12V

23 System Voltage V 10 - 15 10 - 15 10 - 15 This displays the system voltage measured by the ECM at
ignition feed.

24 Main Relay Active/ Active Active Active This displays operating status for the ECM main relay. This
Inactive should display "Active" when the key switch is turned on
and while engine is running.

25 Glow Time Relay Active 0V/ Inactive Inactive Inactive This displays operating status for the glow relay. This
12V 12V
Inactive12V 12V should display "Inactive 12V" when the engine is warm
upped.

26 Check Engine Light On/Off Off Off Off This displays operating status for the Check Engine Lamp.
This should display "On" when the Check Engine Lamp is
27 Glow Time Telltale On/Off Off Off Off turned on.
700 700
28 Desired Engine Idle rpm 700 This displays operating status for the glow indicator lamp.
Speed Inactive Inactive This should display "On" when the glow lamp is turned on.
12V 12V
29 A/C Request Active 0V/ Inactive The desired engine idle speed that the ECM commanding.
Inactive Inactive The ECM compensates for various engine loads based on
Inactive 12V 12V engine coolant temperature.

30 Immobilizer Active/ Inactive This displays operating status of the A/C compressor. This
Inactive should display "Active 0V" when the compressor relay is
operated.

This should display "Inactive" when the immobilizer is
correctly operated.

31 Immobilizer Signal Received/ Not Not Not This should display "Not Received" when the immobilizer is
Not Received Received Received not activated.

Received

32 Immobilizer Function Yes/ No Yes Yes Yes This should display "Yes" when the immobilizer is correctly
Programmed 85 - 90 85 - 90 85 - 90 programmed.

33 EGR Pulse Ratio % This displays the duty signal from the ECM to control the
EGR flow amount.
(Exhaust Gas

Recirculation)

6E–92 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS

MISCELLANEOUS TEST F3: Engine Speed (RPM) Control
When the Tech 2 is operated, "Desired Idle Speed"
The state of each circuit can be tested by using increases 50rpm-by-50rpm up to 1200rpm.
miscellaneous test menus. Especially when DTC The circuit is correct if engine speed is changed in
cannot be detected, a faulty circuit can be diagnosed by accordance with this operation.
testing each circuit by means of these menus.
Even DTC has been detected, the circuit tests using Engine Speed (RPM) Control
these menus could help discriminate between a
mechanical trouble and an electrical trouble. Engine Speed 850 rpm
Connect Tech 2 and select "Powertrain", "4JA1-TC
Bosch" or "4JH1-TC Bosch" & "Miscellaneous Test". Desired Idle Speed 850 rpm

F0: Lamps Injection Quantity 7.5 mg/ strk
F0: Glow Time Telltale Test
When the Tech 2 is operated, "Glow Time Indicator • Press "Increase" key.
Lamp" is turned on or off. Then, Desired Idle speed is increases
The circuit is correct if the "Glow Time Indicator Lamp" 50rpm-by-50rpm up to 1200rpm. Engine speed is
in the instrument panel is turned on or off in accordance also
with this operation.

F1: Relays
F0: Glow Time Relay Test
When the Tech 2 is operated, glow relay turns ON or
OFF.
The circuit is correct if glow relay is operated in
accordance with this operation.

F2: Solenoids
F0: EGR Solenoid Test
When the Tech 2 is operated, control duty ratio of EGR
EVRV changes to 5% to 95%.
The circuit is correct if glow relay is operated in
accordance with this operation.

EGR Solenoid Test

Desired Mass Air Flow 470 mg/strk

Mass Air Flow 450 mg/strk

Engine Speed 700 rpm

Exhaust Gas Recirculation 95%

• Press "Active" key.
Then, EVRV duty ratio increases to 95%

• Press "Inactive key".
EVRV duty ratio decreases to 5%

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–93

Plotting Snapshot Graph

This test selects several necessary items from the data
list to plot graphs and makes data comparison on a long
term basis. It is an effective test particularly in emission
related evaluations.

For trouble diagnosis, you can collect graphic data
(snap shot) directly from the vehicle.
You can replay the snapshot data as needed. Therefore,
accurate diagnosis is possible, even though the vehicle
is not available.

6E–94 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Plotting Graph Flow Chart (Plotting graph after obtaining vehicle information)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–95
Flow Chart for Snapshot Replay (Plotting Graph)

6E–96 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
SNAPSHOT DISPLAY WITH TIS2000

Procedures for transferring and displaying Tech2 By analyzing these data in various methods, trouble
snapshot data by using TIS2000 [Snapshot Upload] conditions can be checked.
function is described below. Snapshot data is displayed by executing the three steps
Snapshot data can be displayed with [Snapshot Upload] below shown:
function included in TIS2000.

1. Record the snapshot data, in Tech2.

2. Transfer the snapshot data to PC.