engine ISUZU TF SERIES 2004 Workshop Manual

6E-294 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
5
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 -

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-295
DIAGNOSTIC TROUBLE CODE (DTC) P0602 ECU PROGRAMMING ERROR

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)
51 P0602 - ECU Programming
Error ECM memory area error. Engine control disabled.

CIRCUIT DESCRIPTION
The engine control module (ECM) used in this vehicle
utilizes an electrically erasable programmable read-only
memory (EEPROM). The EEPROM contains program
information and the calibrations required for engine,
transmission, and engine diagnostics operation.
Unlike the PROM used in past applications, the
EEPROM is not replaceable.

DIAGNOSTIC AIDS
Check for following conditions.
 When reprogramming operation is stopped unde
r
Service Programming System (SPS), DTC P0602 will
be set.
 When non programmed ECM (service ECM) is used
without Service Programming System (SPS), DTC
P0602 will be set.



Diagnostic Trouble Code (DTC) P0602 ECU Programming Error

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 P0602 stored as "Present Failure"?
- Go to Step 3 Refer to
Diagnostic Aids
3
Download the latest software to the ECM. "SPS
(Service Programming System) is necessary."
Is the action complete?
- Verify repair -

6E-296 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1508 (FLASH CODE 22) IDLE AIR
CONTROL SYSTEM LOW/CLOSED
DIAGNOSTIC TROUBLE CODE (DTC) P1509 (FLASH CODE 22) IDLE AIR
CONTROL SYSTEM HIGH/OPEN



RTW36EMF000201

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-297
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)
P1508 B Idle Air Control System
Low/Closed 1. No DTC relating to MAF sensor, IAT sensor, ECT sensor,
TPS, CMP sensor, CKP sensor, VSS and system voltage.
2. Engine speed is between 675rpm and 6000rpm.
3. Engine coolant temperature is more than 75
C.
4. Intake air temperature is between -10
C and 80
C.
5. Vehicle is stopping.
6. Small amount of intake air through the idle air control
valve. (Idle air control valve is sticking at close position.)
Above conditions are met for 2 seconds. 22
P1509 B Idle Air Control System
High/Open 1. No DTC relating to MAF sensor, IAT sensor, ECT sensor,
TPS, CMP sensor, CKP sensor, VSS and system voltage.
2. Engine speed is between 675rpm and 6000rpm.
3. Engine coolant temperature more than 75
C.
4. Intake air temperature is between -10
C and 80
C.
5. Vehicle is stopping.
6. Large amount of intake air through the idle air control
valve. (Idle air control valve is sticking at open position.)
Above conditions are met for 2 seconds. Fuel cut is operated at high idle
speed.

CIRCUIT DESCRIPTION
The engine control module (ECM) controls engine idle
speed by adjusting the position of the idle air control
(IAC) motor pintle. The IAC is a bi-directional steppe
r
motor driven by two coils. The ECM applies current to
the IAC coils in steps (counts) to extend the IAC pintle
into a passage in the throttle body to decrease air flow.
The ECM reverses the current to retract the pintle,
increasing air flow. This method allows highly accurate
control of idle speed and quick response to changes in
engine load. If the ECM detects a condition where too
low of an idle speed is present and the ECM is unable
to adjust idle speed by increasing the IAC counts, DTC
P1508 or P1509 will set, indicating a problem with the
idle control system.

DIAGNOSTIC AIDS
Check for the following conditions:
 Poor connection at ECM or IAC motor –Inspec
t
harness connectors for backed-out terminals,
improper mating, broken locks, improperly formed o
r
damaged terminals, and poor terminal-to-wire
connection.
 Damaged harness – Inspect the wiring for damage.
 Restricted air intake system – Check for a possible
collapsed air intake duct, restricted air filter element,
or foreign objects blocking the air intake system.

6E-298 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1508 (Flash Code 22) Idle Air
Control System Low/Closed
Diagnostic Trouble Code (DTC) P1509 (Flash Code 22) Idle Air
Control System High/Open
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 P1508 or P1509 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 P1508 or P1509 stored in this ignition
cycle?
- Go to Step 4 Refer to
Diagnostic Aids
and Go to Step 4
4
Check for the following conditions.

Objects blocking the Idle Air Control (IAC) Valve.

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 5
5
Check for poor/faulty connection at the IAC Valve or
ECM connector.
If a poor/faulty connection is found, repair the faulty
terminal.
Was the problem found?
E-61(B)







E-70






- Verify repair Go to Step 6

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-299
Step Action Value (s) Yes No
6
Remove the IAC Valve and visually check.
Was the problem found?
- Go to Step 12 Go to Step 7
7
Using the DVM and check the IAC Valve coil at IAC
Valve.
1. Ignition "Off", engine "Off".
2. Disconnect the IAC Valve connector.
3. Check the coil resistance.
Does the tester indicate standard resistance as shown
in the following table?
IAC Valve














Measurement Terminal Resistance ()
1 - 2 Approximately 50
2 - 3 Approximately 50
1 – 3 Approximately 100
4 - 5 Approximately 50
5 - 6 Approximately 50
4 - 6 Approximately 100
-
Go to Step 8
Go to Step 12
8
Using the DVM and check the IAC Valve power supply
circuit.
1. Ignition "Off", engine "Off".

2. Disconnect the IAC Valve connector and ECM
main relay
3. Check the circuit for open circuit.
Was the problem found?
X-13E-70











-
Repair faulty
harness and
verify repair
Go to Step 9

6E-300 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
9

Using the DVM and check the IAC Valve circuit.
Breaker box is available:
1. Ignition "Off", engine "Off".
2. Install the breaker box as type B. (ECM connection)
3. Using the Tech 2, ignition "On" and engine "Off".
4. Select the "Miscellaneous Test" and perform the
"IAC Control" in the "IAC System".
5. Operate the Tech 2 in accrodance with procedure.
Does the DVM indicate correct characteristic as
shown in the following table, when the IAC Valve is
operating step by step?
B13B14 Breaker BoxB17 B16
VVVV


Measurement Point IACV steps at 0, 20, 40,
160 IACV steps at 10, 30, 50,
150
Coil A High (Breaker Box 53 & GND) Less than 1V Battery voltage
Coil A Low (Breaker Box 56 & GND) Battery voltage Less than 1V
Coil B High (Breaker Box 54 & GND) Less than 1V Battery voltage
Coil B Low (Breaker Box 57 & GND) Battery voltage Less than 1V

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-301
Step Action Value (s) Yes No
Breaker box is not available:
1. Using the Tech 2, ignition "On" and engine "Off".
2. Select the "Miscellaneous Test" and perform the
"IAC Control" in the "IAC System".
3. Operate the Tech 2 in accordance with procedure.
Does the DVM indicate correct characteristic as
shown in the following table, when the IAC Valve is
operating step by step?
E-61(B)
VVVV









Measurement Point IACV steps at 0, 20, 40,
160 IACV steps at 10, 30, 50,
150
Coil A High (ECM E61 connector 13 & GND) Less than 1V 10 - 14.5 V
Coil A Low (ECM E61 connector 16 & GND) 10 - 14.5 V Less than 1V
Coil B High (ECM E61 connector 14 & GND) Less than 1V 10 - 14.5 V
Coil B Low (ECM E61 connector 17 & GND) 10 - 14.5 V Less than 1V
-
Go to Step 14 Fixed at less than
1V: Go to Step
10
Fixed at battery
voltage: Go to
Step 11

6E-302 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
10
Using the DVM and check the IAC Valve 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 IAC Valve connector.
4. Check the circuit for open or short to ground circuit.
Was the problem found?
B13B14 Breaker BoxB17 B16
E-70













B13B14 Breaker BoxB17 B16









Breaker box is not available:
1. Ignition "Off", engine "Off".
2. Disconnect the IAC Valve connector.
3. Check the circuit for open or short to ground circuit.
Was the problem found?
E-61(B)
E-70




















E-61(B)










- Repair faulty
harness and
verify repair Go to Step 14

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-303
Step Action Value (s) Yes No
11
Using the DVM and check the IAC Valve circuit.
1. Ignition "On", engine "Off".
2. Disconnect the IAC Valve connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicate voltage?
E-70
VVVV






-
Repair faulty
harness and
verify repair
Go to Step 14
12
Substitute a known good IAC Valve and recheck.
Was the problem solved?
- Go to Step 13 Go to Step 14
13
Replace the IAC Valve.
Was the problem solved?
- Verify repair Go to Step 14
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 -