2004 ISUZU TF SERIES 4jh1

6E–196 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0251 (SYMPTOM CODE 6)
(FLASH CODE 53) INJECTION PUMP MALFUNCTION
DIAGNOSTIC TROUBLE CODE (DTC) P0251 (SYMPTOM CODE 7)
(FLASH CODE 53) INJECTION PUMP MALFUNCTION
DIAGNOSTIC TROUBLE CODE (DTC) P0251 (SYMPTOM CODE 9)
(FLASH CODE 53) INJECTION PUMP MALFUNCTION
DIAGNOSTIC TROUBLE CODE (DTC) P0251 (SYMPTOM CODE A)
(FLASH CODE 53) INJECTION PUMP MALFUNCTION
DIAGNOSTIC TROUBLE CODE (DTC) P0251 (SYMPTOM CODE B)
(FLASH CODE 53) INJECTION PUMP MALFUNCTION
DIAGNOSTIC TROUBLE CODE (DTC) P0251 (SYMPTOM CODE D)
(FLASH CODE 53) INJECTION PUMP MALFUNCTION
DIAGNOSTIC TROUBLE CODE (DTC) P0251 (SYMPTOM CODE E)
(FLASH CODE 53) INJECTION PUMP MALFUNCTION

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–197
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM is calculates an injection quantity and an
injection timing using the various sensors. And the PSG
controls the high pressure solenoid valve depending on
programmed pump map data.
The signal of desired injection quantity and actual injec-
tion quantify are ex changed via the CAN-bus between
the PSG and ECM.
If the relation of engine speed signal and doubled pump
camshaft speed signal ex cessively large, DTC P0251
(Symptom Code 7) will be stored.
If the CAN high or low circuit is defected, DTC P0251
(Symptom Code E) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM and PSG-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 “Injection Quantity” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.
Diagnostic Trouble Code (DTC) P0251 (Symptom Code 6) (Flash Code 53)
Injection Pump Malfunction
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
53 P0251 6 ON Injection Pump Malfunction 1. No pump camshaft speed
se nsor erro r.
2. High pressure solenoid
v a lv e co ntro l pulse w idth
doe s no t ma tch with
desired fuel injection quan-
tity. 1. MAB (fuel cutoff solenoid
valve) is operated.
2. Desired injection quantity
becomes 0mg/strk.
7 ON Injection Pump Malfunction 1. No pump camshaft speed
se nsor erro r.
2. No CKP senso r e rror.
3. Difference of engine speed
and doubled pump cam-
shaft speed is more than
720rpm (4JA1-TC) or 690
rpm (4JH1-TC).
9 ON Injection Pump Malfunction No pump map programmed in
the PSG (pump co ntrol unit)
or PSG malfunction.
A ON Injection Pump Malfunction EEPROM or A/D converter
malfunctio n in the PSG (pump
control unit).Fuel inje ctio n qua ntity is
reduced.
B ON Injection Pump Malfunction PSG (pump control unit) rec-
ognized high pressure sole -
noid valve drive circuit error.No fa il-sa fe fun ctio n.
D ON Injection Pump Malfunction PSG (pump control unit) could
no t me asure the high pres-
sure solenoid valve drive volt-
age.
E ON Injection Pump Malfunction ECM could not accept PSG
(pump co ntrol unit) messa ge.1. MAB (fuel cutoff solenoid
valve) is operated.
2. Desired injection quantity
becomes 0mg/strk.
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

6E–198 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
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 P0251 (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 P0251 (Symptom Code 6) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
4 Replace the injection pump assembly.
Is the action complete?—Verify repair— Step Action Value(s) Yes No

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –199
Diagnostic Trouble Code (DTC) P0251 (Symptom Code 7) (Flash Code 53)
Injection Pump Malfunction
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 P0251 (Symptom Code 7) 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 P0251 (Symptom Code 7) stored in this
ignition cycle? —Go to Step 4 Refer to
Diagnostic Aids and Go to Step
4
4 Was the DTC P0335 (Symptom Code B), P0335 (Symptom Code D) or P1335 (Symptom Code A)
stored at the same time?
— Go to DTC
Chart P0335 (Symptom Code B)
(Symptom
Code D) or P1335
(Symptom Code A) Go to Step 5
5 Check for poor/faulty connection at the ECM or PSG (pump control unit) connector. If a poor/faulty
connection is found, repair the faulty terminal.
Was the problem found?
— Verify repair Go to Step 6
91
8C-57(B) E-6

6E–200 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
6 If a oscilloscope is available, monitor the CKP sensor
output signal. Does the oscilloscope indicate correct
wav e form?
—Go to Step 13Not available:
Go to Step 7
Fix ed at low:
Go to Step 7
Fix ed at High:
Go to Step 8 Step Action Value(s) Yes No
Cra nksha ft Po sitio n (CKP) Sensor & TDC Output Signal
Reference Wave Form
CH1
0V
CH2
0V
Mea sure me nt Terminal: CH1: 90(+) / CH2: 91(+) GND(-)
Mea sure me nt Scale: CH1: 50V/div / CH2: 10V/div 1ms/div
Mea sure me nt Co ndition: Approx imately 2000rpm

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E –201
7 Using the DVM and check the CKP sensor output
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 ECM connector.
3. Disconnect the PSG (pump control unit) 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 8
8 Using the DVM and check the CKP sensor output 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 specified value?
Less than 1V Go to Step 9 Repair faulty
harness and verify repair
Step Action Value(s) Yes No
E-691Breaker Box




918
C-57(B) E-6
8
V
E-6

6E–202 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
9 Check any accessory parts which may cause electric
interference or magnetic interference.
Was the problem found?—Remove the
accessory parts
and verify repair Go to Step 10
10 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 11
11 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 12Go to Step 13
12 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—
13 Replace the injection pump assembly.
Is the action complete?—Verify repair— Step Action Value(s) Yes No

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–203
Diagnostic Trouble Code (DTC) P0251 (Symptom Code 9) (Flash Code 53)
Injection Pump 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 P0251 (Symptom Code 9) 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 P0251 (Symptom Code 9) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
4 Replace the injection pump assembly.
Is the action complete?—Verify repair—