Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 56

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

6E–219

5

Using the DVM and check the A/C compressor relay. 

1. Ignition “Off”, engine “Off”. 

2. Remove the A/C compressor relay from the relay

box. 

3. Check the relay coil. 

Was the DVM indicated specified value?

Continuity

Go to Step 6

Replace A/C 

compressor 

relay and verify 

repair

6

Using the DVM and check the A/C compressor relay
power supply circuit. 

1. Ignition “On”, engine “Off”. 

2. Remove the A/C compressor relay from the relay

box. 

3. Check the circuit for open or short to ground

circuit. 

Was the DVM indicated specified value?

Battery 
voltage

Go to Step 8

Go to Step 7

7

Repair the open or short to ground circuit between the
ECM main relay and A/C compressor relay. 
Is the action complete?

—

Verify repair

—

Step

Action

Value(s)

Yes

No

5

3

A/C Compressor Relay

5

V

X-5

4JA1-TC

X-10

4JH1-TC

5

1

X-5

4JA1-TC

X-10

4JH1-TC

X-4

6E–220

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

8

Using the DVM and check the A/C compressor relay
ground circuit. 
Breaker box is available: 

1. Ignition “Off”, engine “Off”. 

2. Install the breaker box as type A. (ECM

disconnected) 

3. Remove the A/C compressor relay from the relay

box. 

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 A/C compressor relay from the relay

box. 

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

41

3

X-5

4JA1-TC

X-10

4JH1-TC

41

3

C-56

X-5

4JA1-TC

X-10

4JH1-TC

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

6E–221

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 immobiliser system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobiliser System-ECM replacement” for
the ECM/Immobiliser linking procedure.

—

Verify repair

—

Step

Action

Value(s)

Yes

No

6E–222

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

Diagnostic Trouble Code (DTC) P0645 (Symptom Code 8) (Flash Code 46) A/C 

Compressor Relay Circuit Voltage High

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 P0645 (Symptom Code 8) 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 P0645 (Symptom Code 8) stored in this
ignition cycle?

—

Go to Step 4

Refer 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 immobiliser system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobiliser System-ECM replacement” for
the ECM/Immobiliser 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 immobiliser system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobiliser System-ECM replacement” for
the ECM/Immobiliser linking procedure.

—

Verify repair

—