Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 81

4JA1-TC/4JH1-TC ENGINE DRIVEABILITY AND EMISSIONS

6E–319

Diagnostic Trouble Code (DTC) P1651 (Symptom Code B) (Flash Code 45) CAN 

Receives 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 As Stored By ECU” in

“F0: Diagnostic Trouble Codes”. 

Is the DTC P1651 (Symptom Code B) 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 P1651 (Symptom Code B) stored in this
ignition cycle?

—

Go to Step 4

Refer to 

Diagnostic Aids 

and Go to Step 

4

4

Was the DTC P1650 (Symptom Code A) stored at the
same time?

—

Go to DTC 

Chart P1650 

(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 as necessary. 
Was the problem found?

—

Verify repair

Go to Step 6

6

Visually check the PSG (pump control unit). 
Was the problem found? 

—

Go to Step 19

Go to Step 7

7

Using the DVM and check the CAN high circuit.

1. Ignition “Off”, engine “Off”. 

2. Disconnect the ECM connector and PSG (pump

control unit) connector. 

3. Check the circuit for short to CAN low circuit. 

Was the DVM indicated specified value?

No continuity

Go to Step 8

Repair faulty 
harness and 

verify repair

100

99

1

2

C-57

E-6

2

1

E-6

6E–320

4JA1-TC/4JH1-TC 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-81 

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

100

2

E-6

100

2

C-57

E-6

4JA1-TC/4JH1-TC ENGINE DRIVEABILITY AND EMISSIONS

6E–321

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-81 

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

99

1

E-6

99

1

C-57

E-6

2

V

E-6

6E–322

4JA1-TC/4JH1-TC 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 13

Go 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

100

2

C-57

E-6

1

V

E-6

99

1

C-57

E-6

6

E-6