Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 49

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

6E–191

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 P0500 (Symptom Code 1) stored in this
ignition cycle?

—

Go to Step 4

Refer to 

Diagnostic Aids 

and Go to Step 

4

4

Perform test drive and check the speed meter.
Does the speed meter indicate correct vehicle speed.

—

Go to Step 5

Go to Step 6

5

Perform test drive and use the Tech 2.  
Monitor the “Vehicle Speed” in the data display. 
Does the Tech 2 indicate correct vehicle speed as
same as the speed meter indication in the instrument
panel?

—

Go to Step 14

Go to Step 7

6

Remove the VSS from the housing case and visually
check. 
Was the problem found? 

—

Go to Step 8

Go to Step 7

7

Using the DVM and check the VSS signal.

1. Ignition “On”, vehicle “Run (lift up)”. 

2. Measure the VSS output voltage at sensor, meter

and ECM. 

Does the tester indicate specified value? 

If a oscilloscope is available, monitor the VSS signal at
each connector connection. Does the oscilloscope
indicate correct wave form? 

Refer to 

Diagnostic Aids 

and Go to Step 

14

Refer the table

Step

Action

Value(s)

Yes

No

Measurement Position

Voltage (V) 

(AC Range)

If No 

Good

VSS terminal 3 & GND

Approximately 6.5 

V at 20km/h

Go to 

Step 8

Meter B23 connector 9 & 
GND

Go to 

Step 9

Meter B23 connector 8 & 
GND

Go to 

Step 11

ECM C56 connector 68 & 
GND

Go to 

Step 12

Vehicle Speed Sensor Reference Wave Form

0V

→

Measurement Scale: 10V/div

50ms/div

Measurement Condition: Vehicle Speed 20km/h
Measurement Terminal: At Engine Control Module

6E–192

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

8

Replace the VSS. 
Is the action complete?

—

Verify repair

9

Using the DVM and check the VSS signal circuit.

1. Ignition “On”, engine “Off”. 

2. Disconnect the meter connector. 

3. Check the circuit for short to power supply circuit. 

Was the DVM indicated specified value? 

Less than 1V

Go to Step 10

Repair faulty 
harness and 

verify repair

10

Using the DVM and check the VSS signal circuit.

1. Ignition “Off”, engine “Off”. 

2. Disconnect the VSS connector and meter

connector. 

3. Check the circuit for open or short to ground

circuit. 

If a open or short to ground circuit is found, repair the
faulty harness and verify repair. 
Is the action complete?

—

Verify repair

—

11

Replace the speed meter. 
Is the action complete?

—

Verify repair

—

Step

Action

Value(s)

Yes

No

9

V

B-23

3

9

E-44

B-23

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

6E–193

12

Using the DVM and check the VSS signal circuit.

1. Ignition “Off”, engine “Off”. 

2. Disconnect the meter connector and ECM

connector. 

3. Ignition “On”. 

4. Check the circuit for short to power supply circuit. 

Was the DVM indicated specified value? 

Less than 1V

Go to Step 13

Repair faulty 
harness and 

verify repair

Step

Action

Value(s)

Yes

No

8

V

B-23

6E–194

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

13

Using the DVM and check the VSS signal 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 meter connector. 

4. Check the circuit for open or shot to ground circuit. 

Was the problem found?

Breaker box is not available: 

1. Ignition “Off”, engine “Off”. 

2. Disconnect the meter connector and ECM

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 14

14

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 15

15

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

8

B-23

68

68

8

B-23

C-56