2004 ISUZU TF SERIES engine

6E–352 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
8 Using the DVM and check the CAN high circuit.
Breaker box is available:
1. Ignition “Off”, engine “Off”.
2. Install the breaker box as type A. (ECM
disconnected) Ref. Page 6E-103
3. Disconnect the PSG (pump control unit)
connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
Breaker box is not available:
1. Ignition “Off”, engine “Off”.
2. Disconnect the PSG (pump control unit)
connector.
3. Check the circuit for open or short to ground
circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 9 Step Action Value(s) Yes No
E-6100Breaker Box




1002 C-57 E-6

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–353
9 Using the DVM and check the CAN low circuit.
Breaker box is available:
1. Ignition “Off”, engine “Off”.
2. Install the breaker box as type A. (ECM
disconnected) Ref. Page 6E-103
3. Disconnect the PSG (pump control unit)
connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
Breaker box is not available:
1. Ignition “Off”, engine “Off”.
2. Disconnect the PSG (pump control unit)
connector.
3. Check the circuit for open or short to ground
circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 10
10 Using the DVM and check the CAN high circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the PSG (pump control unit)
connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated battery voltage or
approximately 5V?
—Go to Step 11 Go to Step 12 Step Action Value(s) Yes No
E-699Breaker Box




991 C-57 E-6
2
V
E-6

6E–354 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
11 Repair the short to voltage circuit between the ECM
and PSG (pump control unit).
Is the action complete?
—Verify repair—
12 Using the DVM and check the CAN low circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the PSG (pump control unit)
connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated battery voltage or
approximately 5V?
—Go to Step 13Go to Step 14
13 Repair the short to voltage circuit between the ECM
and PSG (pump control unit).
Is the action complete?
—Verify repair—
14 Using the DVM and check the PSG (pump control
unit) ground circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the PSG (pump control unit)
connector.
3. Check the circuit for open circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 15 Step Action Value(s) Yes No
1002 C-57 E-6
1
V
E-6
991 C-57 E-6
6
E-6

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–355
15 Check any accessory parts which may cause electric
interference.
Was the problem found?—Remove the
accessory parts
and verify repair Go to Step 16
16 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 17
17 Substitute a known good ECM and recheck.
Was the problem solved?
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. —Go to Step 18Go to Step 19
18 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—
19 Replace the injection pump assembly.
Is the action complete?—Verify repair— Step Action Value(s) Yes No

6E–356 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1690 (SYMPTOM CODE 4)
(FLASH CODE 77) CHECK ENGINE LAMP (MIL) CIRCUIT VOLTAGE LOW
DIAGNOSTIC TROUBLE CODE (DTC) P1690 (SYMPTOM CODE 8)
(FLASH CODE 77) CHECK ENGINE LAMP (MIL) CIRCUIT VOLTAGE HIGH
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The Check Engine Lamp (Malfunction Indicator Lamp
=MIL) should always be illuminated and steady with
ignition “On”. Ignition feed voltage is supplied to the
Check Engine Lamp bulb through the meter fuse. The
ECM turns the Check Engine Lamp “On” by grounding
the check engine lamp driver circuit for a certain time.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
77 P1690 4 OFF Che ck Engine La mp (MIL)
Circuit Voltage LowChe ck engine la mp circuit
open or short to ground cir-
cuit.No fa il-sa fe fun ctio n.
8 OFF Che ck Engine La mp (MIL)
Circuit Voltage HighChe ck engine la mp circuit
sho rt to ground circuit.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–357
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 “Check Engine Lamp” 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) P1690 (Symptom Code 4) (Flash Code 77)
Check Engine Lamp (MIL) 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 P1690 (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 P1690 (Symptom Code 4) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 1. Ignition “On”, engine “Off”.
2. Check the “Check Engine” lamp.
Does the lamp turn “On”?—Go to Step 5Go to Step 6
5 1. Ignition “On”, engine “Off”.
2. Check the “Check Engine” lamp.
Does the lamp turn “Off”?—Go to Step 9Go to Step 7
6 Check the “Check Engine” lamp bulb.
If the bulb is burnt out, repair as necessary.
Was the problem found?—Verify repair Go to Step 7
7 Check for poor/faulty connection at the meter
connector and ECM connector. If a poor/faulty
connection is found, repair as necessary.
Was the problem found?
—Verify repair Go to Step 8
42
17C-56
B-24

6E–358 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
8 Using the DVM and check the “Check Engine” lamp
circuit.
Breaker box is available:
1. Ignition “Off”, engine “Off”.
2. Install the breaker box as type A. (ECM
disconnected) Ref. Page 6E-103
3. Remove the meter connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
Breaker box is not available:
1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Remove the meter connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 9
9 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 10 Step Action Value(s) Yes No
42
Breaker BoxB-24




42
17
C-56
B-24

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–359
10 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— Step Action Value(s) Yes No