2004 ISUZU TF SERIES check engine

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–223
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, andpoor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the DTC P0381 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) P0381 (Symptom Code 4) (Flash Code 67)
Glow Plug Indicator 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 P0381 (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 P0381 (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 glow plug indicator lamp.
Does the lamp turn “On”?—Go to Step 5Go to Step 6
5 1. Ignition “On”, engine “Off”.
2. Check the glow plug indicator lamp.
Does the lamp turn “Off”?—Go to Step 9Go to Step 7
6 Check the glow plug indicator lamp bulb.
If the bulb is burnt out, repair as necessary.
Was the problem found?—Verify repair Go to Step 7

6E –224 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
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
8 Using the DVM and check the glow time telltale 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
Step Action Value(s) Yes No
43
6
30
B-24
C-56
43Breaker BoxB-24




43
6
B-24
C-56

6E–226 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0381 (Symptom Code 8) (Flash Code 67)
Glow Plug Indicator Circuit Voltage 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 P0381 (Symptom Code 8) 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 P0381 (Symptom Code 8) 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
5 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 6—
6 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—

6E–228 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The amount of EGR is controlled by EVRV (electrical
vacuum regulating valve) via the engine control module
(ECM) command signal depends on the engine speed,
operating of the accelerator pedal and engine coolant
temperature.
The EVRV is shaped to control vacuum applied to the
diaphragm chamber of the EGR valve based on duty
signal sent from the ECM.
If the EGR valve is stuck at open position or close
position, DTC P0400 (Symptom Code 3) or DTC P0400
(Symptom Code 5) is stored.
If the EGR EVRV circuit is open or short ground circuit,
DTC P0400 (Symptom Code 4) is stored.
If the EGR EVRV circuit is short to voltage circuit, DTC
P0400 (Symptom Code 8) is stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
EGR valve sticking.
Faulty intake air duct connection.
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 P0400 display on the Tech2 while moving
connectors and wiring harnesses. A change in the
display will indicate the location of the fault.
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
32 P0400 3 ON Ex ha ust Ga s Recircula tio n
Flow Excessive Detected1. Intake air temperature is
between 15 deg.C and 100
deg.C.
2. Engine coolant tempera-
ture is betwee n 55 de g.C
and 100 deg.C (4JA1-TC)
or 35 deg.C and 100 deg.C
(4JH1-TC).
3. Baro me tric pre ssure is
betwee n 850hpa a nd
1100hpa.
4. Small amount of mass air
flo w. (Desired ma ss air flo w
- mass air flow is more than
150mg/strk)Fuel inje ctio n qua ntity is
reduced.
4 ON Ex ha ust Ga s Recircula tio n
Circuit Sho rt to Ground or
Ope n CircuitEGR EVRV circuit open or
sho rt to ground circuit.Fuel inje ctio n qua ntity is
reduced and EGR EVRV 10%
conditio ns a s substitute.
5 ON Ex ha ust Ga s Recircula tio n
Flow Insufficient Detected1. Intake air temperature is
betwee n 15de g.C and 100
deg.C.
2. Engine coolant tempera-
ture is betwee n 55 de g.C
and 100 deg.C (4JA1-TC)
or 35 deg.C and 100 deg.C
(4JH1-TC).
3. Baro me tric pre ssure is
betwee n 850hpa a nd
1100hpa.
4. Large mount of mass air
flo w. (Desire d ma ss air
flo w - mass a ir flow is
below 150 mg/strk)Fuel inje ctio n qua ntity is
reduced.
8 ON Ex ha ust Ga s Recircula tio n
Circuit Sho rt to BatteryEGR EVRV circuit sho rt to
voltage circuit.Fuel inje ctio n qua ntity is
reduced & EGR EVRV 10%
conditio ns a s substitute.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –229
Diagnostic Trouble Code (DTC) P0400 (Symptom Code 3) (Flash Code 32)
Exhaust Gas Recirculation Flow Excessive Detected
Step Action Value(s) Yes No
1Was 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 As Stored By ECU ” in
“ F0: Diagnostic Trouble Codes ”.
Is the DTC P0400 (Symptom Code 3) stored as
“ Present Failure ”? —Go to Step 3 Refer 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 P0400 (Symptom Code 3) stored in this
ignition cycle? —Go to Step 4 Refer to
Diagnostic Aids and Go to Step
4
4 Remove the MAF & IAT sensor assembly and check for the following conditions.
 Objects blocking the air cleaner.
 Objects blocking the MAF sensor.
 Vacuum leaking at intake duct.
 Objects blocking the turbocharger.
If a problem is found, repair as necessary.
Was the problem found? —Verify repair Go to Step 5
5 Remove the MAF & IAT sensor assembly and visually check.
Was the problem found? —Go to Step 6 Go to Step 8
6 Substitute a known good MAF & IAT sensor assembly and recheck.
Was the problem solved? —Go to Step 7 Go to Step 8
7 Replace the MAF & IAT sensor assembly. Is the action complete? —Verify repair —
8 Using the DVM and check the EGR EVRV. 1. Ignition “Off ”, engine “Off ”.
2. Disconnect the EGR EVRV connector.
3. Measure the resistance of EGR EVRV solenoid coil.
Does the tester indicate standard resistance?
Approx imately 14
at 20 °CGo to Step 11 Go to Step 9
1
2
EGR EVRV
1
2

6E–230 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
9 Substitute a known good EGR EVRV and recheck.
Was the problem solved?—Go to Step 10Go to Step 11
10 Replace the EGR EVRV.
Is the action complete?—Verify repair—
11 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair or
Go to Step 13Go to Step 12
12 Inspect the EGR valve.
1. Remove the EGR valve from the engine.
2. Inspect the EGR valve whether pintle valve is
stuck or damaged.
If ex cessive carbon deposit is found, clean up the
EGR valve and inspect damage of the pintle and seat.
Was the problem found?—Verify repair or
Go to Step 13Go to Step 14
13 Replace the EGR valve.
Is the action complete?—Verify repair— Step Action Value(s) Yes No

Vacuum Pump Small Window

6E –232 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0400 (Symptom Code 4) (Flash Code 32)
Exhaust Gas Recirculation Circuit Short to Ground or Open Circuit
Step Action Value(s) Yes No
1Was 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 As Stored By ECU ” in
“ F0: Diagnostic Trouble Codes ”.
Is the DTC P0400 (Symptom Code 4) stored as
“ Present Failure ”? —Go to Step 3 Refer 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 P0400 (Symptom Code 4) stored in this
ignition cycle? —Go to Step 4 Refer to
Diagnostic Aids and Go to S tep
4
4 Check for poor/faulty connection at the EGR EVRV 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 EGR EVRV. 1. Ignition “Off ”, engine “Off ”.
2. Disconnect the EGR EVRV connector.
3. Measure the resistance of EGR EVRV solenoid coil.
Does the tester indicate standard resistance?
Approx imately 14
at 20 °CGo to Step 6Go to Step 9
9712
C-115
C-57
1
2
EGR EVRV
1
2

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –233
6 Using the DVM and check the EGR EVRV power
supply circuit.
1. Ignition “On ”, engine “Off ”.
2. Remove the EGR EVRV connector.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
10-14.5 V Go to Step 8Go to Step 7
7 Repair the open circuit between the ECM main relay and EGR EVRV.
Is the action complete? —Verify repair —
8 Using the DVM and check the EGR EVRV 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 EGR EVRV 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 EGR EVRV 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 11
9 Substitute a known good EGR EVRV and recheck. Was the problem solved? —Go to Step 10 Go to Step 11
Step Action Value(s) Yes No
V
1
C-115
C-11597Bre ak er Box




97
2
C-115
C-57