2004 ISUZU TF SERIES ECU

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–275
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 P0703 (Symptom Code A) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check the “Stop Lamp fuse (15A)”.
If the fuse is burnt out, repair as necessary.
Was the problem found?—Verify repair Go to Step 5
5 Check for poor/faulty connection at the brake switch
or ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
—Verify repair Go to Step 6
6 Using the DVM and check the brake switch 1.
1. Ignition “Off”, engine “Off”.
2. Remove the brake switch connector at the brake
pedal.
3. Check the brake switch 1.
Was the DVM indicated specified value?
Pedal is not
stepped on:
Continuity
Pedal stepped
on: No
continuity Go to Step 7Replace pedal
switch and
verify repair
7 Using the DVM and check the brake switch 1 power
supply circuit.
1. Ignition “Off”, engine “Off”.
2. Remove the brake switch connector from the
brake switch.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
10-14.5V Go to Step 9Go to Step 8 Step Action Value(s) Yes No
301
2 C-56 C-44




Brake Switch
V
1C-44

6E–278 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0703 (Symptom Code B) (Flash Code 25)
Brake 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 P0703 (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 P0703 (Symptom Code B) 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 brake switch
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 brake switch 2.
1. Ignition “Off”, engine “Off”.
2. Remove the brake switch connector at the brake
pedal.
3. Check the brake switch 2.
Was the DVM indicated specified value?
Pedal is not
stepped on:
No continuity
Pedal stepped
on: Continuity Go to Step 6Replace pedal
switch and
verify repair
653
4 C-56 C-44




Brake Switch

6E–282 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0704 (Symptom Code 6) (Flash Code 57)
Clutch Switch Input 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 P0704 (Symptom Code 6) 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 P0704 (Symptom Code 6) 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 clutch switch
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 clutch switch.
1. Ignition “Off”, engine “Off”.
2. Remove the clutch switch connector at the clutch
pedal.
3. Check the clutch switch.
Was the DVM indicated specified value?
Pedal is not
stepped on:
Continuity
Pedal stepped
on: No
continuity Go to Step 6Replace pedal
switch and
verify repair
311
2
C-56 C-77
Clutch Sw itch



4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–285
DIAGNOSTIC TROUBLE CODE (DTC) P1105 (SYMPTOM CODE 1)
(FLASH CODE 86) BAROMETRIC PRESSURE SENSOR CIRCUIT HIGH INPUT
DIAGNOSTIC TROUBLE CODE (DTC) P1105 (SYMPTOM CODE 2)
(FLASH CODE 86) BAROMETRIC PRESSURE SENSOR CIRCUIT LOW INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM monitors the barometric pressure signal at
inside of the ECM. If the sensor with malfunction, DTC
P1105 (Symptom Code 1) or P1105 (Symptom Code 2)
will be stored.
Diagnostic Aids
If the DTC P1105 is stored, sensor or circuit of ECM
inside is failed.
Diagnostic Trouble Code (DTC) P1105 (Sy mptom Code 1) (Flash Code 86)
Barometric Pressure Sensor Circuit High Input
Diagnostic Trouble Code (DTC) P1105 (Sy mptom Code 2) (Flash Code 86)
Barometric Pressure Sensor Circuit Low Input
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
86 P1105 1 ON Ba rome tric Pressure Se nsor
Circuit High InputBa rome tric pressure senso r
output voltage is more than
4.4V.ECM use s 1013hpa condition
as substitute .
2 ON Ba rome tric Pressure Se nsor
Circuit Lo w InputBa rome tric pressure senso r
output voltage is below 1.5V.
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 P1105 (Symptom Code 1) or P1105
(Symptom Code 2) 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 P1105 (Symptom Code 1) or P1105
(Symptom Code 2) stored in this ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
4 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 5

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–289
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 P1120 (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 P1120 (Symptom Code 1) 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 TPS or ECM
connector. If a poor/faulty connection is found, repair
as necessary.
Was the problem found?
—Verify repair Go to Step 5
5 Visually check the TPS.
Was the problem found? —Go to Step 12Go to Step 6 Step Action Value(s) Yes No
4939
57
23 1C-56
E-22

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–293
Diagnostic Trouble Code (DTC) P1120 (Sy mptom Code 7) (Flash Code 21)
Pedal/Throttle Position Sensor Voltage Supply Circuit High Input
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 P1120 (Symptom Code 7) 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 P1120 (Symptom Code 7) 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 TPS or ECM
connector. If a poor/faulty connection is found, repair
as necessary.
Was the problem found?
—Verify repair Go to Step 5
5 Visually check the TPS.
Was the problem found? —Go to Step 8Go to Step 6
4939
57
23 1C-56
E-22

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–295
Diagnostic Trouble Code (DTC) P1120 (Sy mptom Code 9) (Flash Code 21)
Pedal/Throttle Position Sensor Voltage Supply Circuit Low Input
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 P1120 (Symptom Code 9) stored as
“Present Failure”?—Go to Step 3Refer to
Diagno stic 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 P1120 (Symptom Code 9) 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 TPS or ECM
connector. If a poor/faulty connection is found, repair
as necessary.
Was the problem found?
—Verify repair Go to Step 5
5 Visually check the TPS.
Was the problem found? —Go to Step 10Go to Step 6
4939
57
23 1C-56
E-22

6E–298 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1120 (Sy mptom Code D) (Flash Code 21)
Pedal/Throttle Position Sensor Brake Switch Error
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 P1120 (Symptom Code D) 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 P1120 (Symptom Code D) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Visually check the TPS.
Check for the following conditions.
Accelerator pedal sticking.
If a problem is found, repair as necessary.
Was the problem found? —Verify repair Go to Step 5
5 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Throttle Position” in the data display.
Does the Tech 2 indicate correct “Throttle Position”
from 0% to 100% depending on accelerator pedal
operation?—Go to Step 7Go to Step 6
6 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Throttle Position” in the data display.
3. Adjust the TPS within 0% to 100%.
Was the problem solved?—Verify repair Go to Step 11
7 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Brake Switch 1” and “Brake Switch 2”
in the data display.
Does the Tech 2 indicate “Inactive” when the brake
pedal was not stepped on?—Go to Step 13Go to Step 8
8 Adjust the brake switch.
Was the problem solved?—Verify repair Go to Step 9
9 Substitute a known good brake switch and recheck.
Was the problem solved?—Go to Step 10Go to Step 13
10 Replace the brake switch.
Is the action complete?—Verify repair—
11 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 12Go to Step 13
12 Replace the TPS.
Is the action complete?—Verify repair—