check engine ISUZU TF SERIES 2004 Workshop Manual

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-181
Step Action Value (s) Yes No
6
Check for the following conditions.

Objects blocking the throttle valve.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 7
7
Check for poor/faulty connection at the TPS or ECM
connector. If a poor/faulty connection is found, repair
the faulty terminal.
Was the problem found?
E-61(B)




E-68




- Verify repair Go to Step 8
8
Visually check the TPS.
Was the problem found?
- Go to Step 12 Go to Step 9
9
Using the DVM and check the TPS signal circuit.
1. Ignition "On", engine "Off".
2. Disconnect the TPS connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
E-68


V


Less than 1V
Go to Step 10
Repair faulty
harness and
verify repair
10
Check any accessory parts which may cause electric
interference.
Was the problem found?
- Remove the
accessory parts
and verify repair Go to Step 11
11
Check the shield wire for open or short circuit.
Was the problem found?
- Verify repair Go to Step 12
12
Substitute a known good TPS and recheck.
Was the problem solved?
- Go to Step 13 Go to Step 14
13
Replace the TPS.
Is the action complete?
- Verify repair -

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-183
DIAGNOSTIC TROUBLE CODE (DTC) P0122 (FLASH CODE 21) THROTTLE
POSITION SENSOR CIRCUIT LOW INPUT



RUW46EMF000101

Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
21 P0122 A Throttle Position
Sensor Low Input TPS output voltage is below 0.24V. The ECM uses default throttle
position value based on mass air
flow and engine speed.

CIRCUIT DESCRIPTION
The TPS circuit provides a voltage signal that changes
relative to throttle blade angle. The signal voltage will
vary from below 0.6 volts at closed throttle to about 4.5
volts at wide open throttle (WOT).
The TPS signal is used by the Engine Control Module
(ECM) for fuel control and many of the ECM-controlled
outputs.

DIAGNOSTIC AIDS
Check for the following conditions:
 Poor connection at ECM – Inspect harness
connectors for backed-out terminals, imprope
r
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
 Damaged harness –Inspect the wiring harness fo
r
damage. If the harness appears to be OK, observe
the throttle position display on the Tech 2 while
moving connectors and wiring harnesses related to
the TPS. A change in the display will indicate the
location of the fault.
If DTC P0122 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

6E-184 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0122 (Flash Code 21) Throttle Position
Sensor Circuit Low Input
Step Action Value (s) Yes No
1
Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go 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 By Priority" in "F0:
Diagnostic Trouble Code".
Is the DTC P0122 stored as "Present Failure"?
- Go to Step 3 Refer to
Diagnostic Aids
and Go to Step 3
3
1. Using the Tech2, ignition "On" and engine "Off".
2. Select "Clear DTC Information" with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the "F5: Failed
This Ignition" in "F2: DTC Information"
Was the DTC P0122 stored in this ignition cycle?
- Go to Step 4 Refer 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?
E-61(B)




E-68




- Verify repair Go to Step 5
5
Visually check the TPS.
Was the problem found?
- Go to Step 10 Go to Step 6

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-185
Step Action Value (s) Yes No
6
Using the DVM and check the TPS.
1. Ignition "Off", engine "Off".
2. Disconnect TPS connector.
3. Measure the resistance of TPS.
Does the tester indicate standard resistance as shown
in the following table?
TPS










Measurement Terminal Resistance (

) 1 - 2 Approximately 4.7k

at idle position Approximately 1.0k

at WOT 2 – 3 Approximately 0.6k

at idle position Approximately 4.3k

at WOT
1 – 3 Approximately 5.0k

at idle position & WOT

Standard
resistance
Go to Step 7
Go to Step 10
7
Using the DVM and check the TPS power supply
circuit.
1. Ignition "On", engine "Off".
2. Disconnect the TPS connector.
3. Check the circuit for open or short to ground circuit.
Was the DVM indicated specified value?
E-68


V


Approximately
5.0V
Go to Step 9
Go to Step 8
8
Repair the open or short to ground circuit between the
ECM and TPS.
Was the problem solved?
E-68


E-61(B)

- Verify repair Go to Step 12

6E-186 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
9

Using the DVM and check the TPS signal circuit.
Breaker box is available:
1. Ignition "Off", engine "Off".
2. Install the breaker box as type A (ECM
disconnected).
Refer to 6E-95 page.
3. Disconnect TPS connector.
4. Check the circuit for open, short to sensor ground
or short to ground circuit.
Was the problem found?
B26B39


Breaker BoxE-68







Breaker box is not available:
1. Ignition "Off", engine "Off".
2. Disconnect the TPS connector and ECM
connector.
3. Check the circuit for open, short to sensor ground
or short to ground circuit.
Was the problem found?
E-61(B)
E-68












-

Repair faulty
harness and
verify repair

Go to Step 12
10
Substitute a known good TPS and recheck.
Was the problem solved?
- Go to Step 11 Go to Step 12
11
Replace the TPS.
Is the action complete?
- Verify repair -
12
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 13

6E-188 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0123 (FLASH CODE 21) THROTTLE
POSITION SENSOR CIRCUIT HIGH INPUT



RUW46EMF000101

Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
21 P0123 A Throttle Position
Sensor High Input TPS output voltage is more than 4.56V. The ECM uses default throttle
position value based on mass air
flow and engine speed.

CIRCUIT DESCRIPTION
The TPS circuit provides a voltage signal that changes
relative to throttle blade angle. The signal voltage will
vary from about 0.6 volts at closed throttle to about 4.5
volts at wide open throttle (WOT).
The TPS signal is one of the most important inputs
used by the Engine Control Module (ECM) for fuel
control and many of the ECM-controlled outputs.
DIAGNOSTIC AIDS
Check for the following conditions:
 Poor connection at ECM – Inspect harness
connectors for backed-out terminals, imprope
r
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
 Damaged harness –Inspect the wiring harness fo
r
damage. If the harness appears to be OK, observe
the TPS display on the Tech 2 while moving
connectors and wiring harnesses related to the TP
sensor. A change in the display will indicate the
location of the fault.
 Faulty TPS –With the ignition key “ON," engine
“OFF," observe the TPS display on the Tech 2 while
slowly depressing the accelerator to wide open
throttle. If a voltage over 4.56 volts is seen at any
point in normal accelerator travel, replace the TPS.
If DTC P0123 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-189
Diagnostic Trouble Code (DTC) P0123 (Flash Code 21) Throttle Position
Sensor Circuit High Input
Step Action Value (s) Yes No
1
Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go 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 By Priority" in "F0:
Diagnostic Trouble Code".
Is the DTC P0123 stored as "Present Failure"?
- Go to Step 3 Refer to
Diagnostic Aids
and Go to Step 3
3
1. Using the Tech2, ignition "On" and engine "Off".
2. Select "Clear DTC Information" with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the "F5: Failed
This Ignition" in "F2: DTC Information"
Was the DTC P0123 stored in this ignition cycle?
- Go to Step 4 Refer 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?
E-61(B)




E-68




- Verify repair Go to Step 5
5
Visually check the TPS.
Was the problem found?
- Go to Step 12 Go to Step 6

6E-190 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
6
Using the DVM and check the TPS.
1. Ignition "Off", engine "Off".
2. Disconnect TPS connector.
3. Measure the resistance of TPS.
Does the tester indicate standard resistance as shown
in the following table?
TPS










Measurement Terminal Resistance ()
1 - 2 Approximately 4.7k at idle position
Approximately 1.0k at WOT
2 – 3 Approximately 0.6k at idle position
Approximately 4.3k at WOT
1 – 3 Approximately 5.0k at idle position & WOT
Standard
resistance
Go to Step 7
Go to Step 12
7
Using the DVM and check the TPS power supply
circuit.
1. Ignition "On", engine "Off".
2. Disconnect the TPS connector.
3. Check the circuit for short to voltage circuit.
Was the DVM indicated specified value?
E-68


V


Approximately
5.0V
Go to Step 9
Go to Step 8
8
Repair the short to voltage circuit between the ECM
and TPS.
Was the problem solved?
E-68


E-61(B)

- Verify repair Go to Step 14

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-191
Step Action Value (s) Yes No
9
Using the DVM and check the TPS signal circuit.
1. Ignition "On", engine "Off".
2. Disconnect the TPS connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
E-68
V




Less than 1V
Go to Step 10
Repair faulty
harness and
verify repair
10
Using the DVM and check the TPS ground circuit.
1. Ignition "On", engine "Off".
2. Disconnect the TPS connector .
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
E-68
V




Less than 1V
Go to Step 11
Repair faulty
harness and
verify repair
11

Using the DVM and check the TPS ground circuit.
Breaker box is available:
1. Ignition "Off", engine "Off".
2. Install the breaker box as type A. (ECM
disconnected).
Refer to 6E-95 page.
3. Disconnect the TPS connector.
4. Check the circuit for open circuit.
Was the problem found?
E-68

B39
Breaker Box

6E-192 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
Breaker box is not available:
1. Ignition "Off", engine "Off".
2. Disconnect the TPS connector and ECM connector.
3. Check the circuit for open circuit.
Was the problem found?
E-61(B)
E-68







- Repair faulty
harness and
verify repair Go to Step 14
12
Substitute a known good TPS and recheck.
Was the problem solved?
- Go to Step 13 Go to Step 14
13
Replace the TPS.
Is the action complete?
- Verify repair -
14
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 15
15
Replace the ECM.
Is the action complete?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. Following
ECM programming, the immobilizer system (if
equipped) must be linked to the ECM. Refer to section
11 “Immobilizer System-ECM replacement” for the
ECM/Immobilizer linking procedure.
- Verify repair -