2004 ISUZU TF SERIES wiring

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–241
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The VSS is a magnet rotated by the transmission output
shaft. The VSS uses a hall element. It interacts with the
magnetic field treated by the rotating magnet. It outputs
pulse signal. The 12 volts operating supply from the
meter fuse.
The engine control module (ECM) calculates the vehicle
speed by VSS.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the DTC P0500 display on the Tech2 while moving
connectors and wiring harnesses. A change in the
display will indicate the location of the fault.
Diagnostic Trouble Code (DTC) P0500 (Symptom Code 1) (Flash Code 24)
Vehicle Speed Sensor Circuit High Input
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
24 P0500 1 ON
at next
ignitio n
cy cleVehicle Spe ed Se nsor Circuit
High InputVehicle speed is more than
200km/h.ECM uses v ehicle spe ed 5km/
h condition as substitute.
AON
at next
ignitio n
cy cleVehicle Speed Sensor Input
Signal Frequency Too HighInput signal frequency is too
high.ECM uses v ehicle spe ed 5km/
h condition as substitute.
BON
at next
ignitio n
cy cleVehicle Spe ed Se nsor Inco r-
re ct Signal1. Engine speed is more than
3200rpm (4JA1-TC) o r
3600rpm (4JH1-TC).
2. Fuel injection quantity is
more than 30mg/strk
(4JA1-TC) or 41mg/strk
(4JH1-TC).
3. Vehicle speed is below
1.5km/h.Fuel injection quantity is
re duced.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P0500 (Symptom Code 1) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Select “F1: Clear DTC Information” in “F0:
Diagnostic Trouble Codes” with the Tech 2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU” in the “F0:
Diagnostic Trouble Codes”.
Was the DTC P0500 (Symptom Code 1) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4

6E–254 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
or low, DTC P0560 (Symptom Code A) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:Poor connection at ECM and PSG-Inspect harness
connectors for backed out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “System Voltage” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.
Diagnostic Trouble Code (DTC) P0560 (Symptom Code 1) (Flash Code 35)
System Voltage Too High
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P0560 (Symptom Code 1) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Select “F1: Clear DTC Information” in “F0:
Diagnostic Trouble Codes” with the Tech 2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU” in the “F0:
Diagnostic Trouble Codes”.
Was the DTC P0560 (Symptom Code 1) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Was the battery jump start cable incorrectly
connecting?—Verify
procedure Go to Step 5
5 1. Using the Tech 2, ignition “On” and engine “On”.
2. Monitor the “System Voltage” in the data display.
3. Load the electrical system by turning on the
headlights, etc..
Does the Tech 2 indicate correct ignition voltage? 10 - 14.5V Go to Step 6Check the
charging
system
6 Is the ECM programmed with the latest software
release?
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”.
Was the problem solved?—Verify repair Go to Step 7

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–261
Circuit Description
The ECM monitors the ignition switch signal on the feed
terminal to the ECM. If the ignition switch signal with
malfunction, DTC P0561 (Symptom Code A) or DTC
P0561 (Symptom Code B) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “Ignition Status” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.
Diagnostic Trouble Code (DTC) P0561 (Symptom Code A) (Flash Code 18)
Ignition Switch Circuit Malfunction
Diagnostic Trouble Code (DTC) P0561 (Symptom Code B) (Flash Code 18)
Ignition Switch Circuit Malfunction
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P0561 (Symptom Code A) or P0561
(Symptom Code B) stored as “Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Select “F1: Clear DTC Information” in “F0:
Diagnostic Trouble Codes” with the Tech 2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU” in the “F0:
Diagnostic Trouble Codes”.
Was the DTC P0561 (Symptom Code A) or P0561
(Symptom Code B)stored in this ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check the “Engine fuse (10A)”.
If the fuse is burnt out, repair as necessary.
Was the problem found?—Verify repair Go to Step 5

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–269
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the DTC P0645 display on the Tech2 while moving
connectors and wiring harnesses.
Diagnostic Trouble Code (DTC) P0645 (Sy mptom Code 4) (Flash Code 46) A/C
Compressor Relay Circuit Voltage Low
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P0645 (Symptom Code 4) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Select “F1: Clear DTC Information” in “F0:
Diagnostic Trouble Codes” with the Tech 2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU” in the “F0:
Diagnostic Trouble Codes”.
Was the DTC P0645 (Symptom Code 4) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the A/C
compressor relay or ECM connector. If a poor/faulty
connection is found, repair as necessary.
Was the problem found?
—Verify repair Go to Step 5
5 Using the DVM and check the A/C compressor relay.
1. Ignition “Off”, engine “Off”.
2. Remove the A/C compressor relay from the relay
box .
3. Check the relay coil.
Was the DVM indicated specified value?
120-150
Go to Step 6Replace A/C
compressor
relay and verify
repair
C-56
X-14








A/C Compressor Relay

 




6E–274 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM monitors the brake switch signal on the feed
terminal to the ECM. If brake switch 1 or 2 circuit with
malfunction, DTC P0703 (Symptom Code A) or P0703
(Symptom Code B) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “Brake Switch 1” and “Brake Switch 2” display on
the Tech2 while moving connectors and wiring
harness related to the sensor.
Diagnostic Trouble Code (DTC) P0703 (Symptom Code A) (Flash Code 25)
Brake Switch Circuit Malfunction
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
25 P0703 A ON Bra ke Switch Circuit
Malfunctio n1. Thro ttle po sitio n is more
tha n 0%.
2. Engine speed is more than
693rpm (4JA1-TC) or
665rpm (4JH1-TC).
3. Vehicle speed is more than
0km/h.
4. Brake switch 1 signal and
brake switch 2 signal are
differently inputted to the
ECM since the ignition
sw it ch w a s tur ne d o n.No fa il-sa fe fun ctio n.
B ON Bra ke Switch Circuit
Malfunctio n1. Thro ttle po sitio n is more
tha n 0%.
2. Engine speed is more than
693rpm (4JA1-TC) or 665
rpm (4JH1-TC).
3. Vehicle speed is more than
0km/h.
4. Brake switch 1 signal and
brake switch 2 signal are
differently inputted to the
ECM.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P0703 (Symptom Code A) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–281
DIAGNOSTIC TROUBLE CODE (DTC) P0704 (SYMPTOM CODE 6)
(FLASH CODE 57) CLUTCH SWITCH INPUT CIRCUIT MALFUNCTION
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM monitors the clutch switch signal on the feed
terminal to the ECM. If clutch switch circuit with
malfunction, DTC P0704 (Symptom Code 6) will be
stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “Clutch Switch” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
57 P0704 6 ON Clutch Switch Input Circuit
Malfunctio nClutch signa l do es no t change
between vehicle speed
1.5km/h and 80km/h since
ignitio n switch was tune d on. No fa il-sa fe fun ctio n.

6E–288 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
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 ECM monitors the TPS supply voltage and TPS
output voltage. The supply voltage is out of range, DTC
P1120 (Symptom Code 7) or P1120 (Symptom Code 9)
will be stored. The output voltage excessively high, DTC
P1120 (Symptom Code 1) will be stored.
If the brake pedal is depressed during accelerator pedal
is depressing, DTC P1120 (Symptom Code D) will be
stored.
If the relation of idle switch and TPS position are
incorrect, DTC P1120 (Symptom Code E) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “Throttle Position”, “Idle Switch”, “Brake Switch 1”
and “Brake Switch 2” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.
Diagnostic Trouble Code (DTC) P1120 (Sy mptom Code 1) (Flash Code 21)
Pedal/Throttle Position Sensor Circuit High Input
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
21 P1120 1 ON Pedal/Throttle Position Sen-
sor Circuit High InputThrottle position sensor out-
put voltage is more than 4.5V.ECM increa ses idle spe ed up
to 1400rpm.
7 ON Pedal/Throttle Position Sen-
sor Voltage Supply Circuit
High InputThrottle position sensor
power supply voltage is more
than 5.2V.
9 ON Pedal/Throttle Position Sen-
sor Voltage Supply Circuit
Lo w InputThrottle position sensor
power supply voltage is below
4.6V.
D ON Pedal/Throttle Position Sen-
sor Brake Switch Error1. Engine speed is more than
1700rpm.
2. Vehicle speed is more than
1.5km/h.
3. When brake pedal is
depressed during accelera-
tor pe da l is de pre ssing.
E ON Pedal/Throttle Position Sen-
sor Idle Position Switch Error1. Whe n idle switch is turne d
o ff, thro ttle positio n se nsor
wa s be lo w 0.35%.
or
2. Whe n idle switch is tune d
on, throttle position sensor
was more than 7.8%.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check

6E–302 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1173 (SYMPTOM CODE 3)
(FLASH CODE 22) FUEL REDUCTION CAUSED BY HIGH COOLANT
TEMPERATURE
DIAGNOSTIC TROUBLE CODE (DTC) P1173 (SYMPTOM CODE 7)
(FLASH CODE 22) FUEL REDUCTION CAUSED BY HIGH FUEL TEMPERATURE
DIAGNOSTIC TROUBLE CODE (DTC) P1173 (SYMPTOM CODE A)
(FLASH CODE 22) FUEL REDUCTION CAUSED BY LOW FUEL TEMPERATURE
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The engine coolant temperature (ECT) sensor is
installed on the coolant stream. High coolant
temperature produces a low resistance. The ECM
supplies 5 volts signal to the ECT sensor through
resisters in the ECM and measures the voltage. The
signal voltage will be low when the engine temperature
is hot.
The fuel temperature sensor is assembled inside of the
pump control unit (PSG). The signal of fuel temperature
is sent via the CAN-bus from the PSG to ECM.
If the engine coolant temperature is ex cessively high
condition, DTC P1173 (Symptom Code 3) will be stored.
If the fuel temperature is ex cessively high or low
condition, DTC P1173 (Symptom Code 7) or P1173
(Symptom Code A) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM and PSG-Inspect harness
connectors for backed out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “Coolant Temperature” or “Fuel Temperature”
display on the Tech2 while moving connectors and
wiring harness related to the sensor.
Diagnostic Trouble Code (DTC) P1173 (Symptom Code 3) (Flash Code 22) Fuel
Reduction Caused By High Coolant Temperature
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
22 P1173 3 OFF Fuel Reduction Caused By
High Coolant TemperatureExcessive high engine cool-
ant temperature is detected.No fa il-sa fe fun ctio n.
7 OFF Fuel Re ductio n Ca used By
High Fuel TemperatureFuel te mpe rature is mo re tha n
100 de g. C.PSG (pump contro l unit) con-
tro ls fuel inje ctio n qua ntity
based on engine speed and
fuel temperature.
A OFF Fuel Re ductio n Ca used By
Low Fuel TemperatureExcessive low fuel tempera-
ture is de te cted.No fa il-sa fe fun ctio n.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P1173 (Symptom Code 3) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3