Glow Plug Relay: Testing and Inspection

Glow Plug Relay, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• wiring diagrams.

Test requirements

• The fuse for the engine electronics OK.

• The Ground (GND) connections at the engine and transmission OK.

• The battery voltage at least 12.5 V.

• The generator OK.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check

Start diagnosis

- Using a Multimeter, check the following wiring connection for voltage.





Specified value: 12.5 V

If the specified value was not obtained:

- Using a Multimeter, check the Glow Plug Relay (J52) socket 2 to the Battery (+) for an open circuit or short to Ground (GND).

- Check the electrical harness connectors for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking relay activation

- Switch the ignition on.

- Using a Multimeter, check the following wiring connection for voltage.





Specified value: 12.5. battery voltage.

- Switch the ignition off.

If the specified value was not obtained:

- Using a Multimeter, check the Glow Plug Relay (J52) socket 2/86 to the Ignition/Starter Switch (D) electrical harness connector terminal for an open circuit.

Specified value: 1.5 ohms.

If the specified value was not obtained:

- Check the Glow Plug Relay (J52) socket 28/15 to the Ignition/Starter Switch (D) electrical harness connector terminal for an open circuit or a short to Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking Ground (GND)

- Using a Multimeter, check the Glow Plug Relay (J52) socket 3/85 to the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) electrical harness connector terminal T80/50 for an open circuit.

Specified value: 1.5 ohms.

If the specified value was not obtained:

- Check the Glow Plug Relay (J52) socket 3/85 to the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) electrical harness connector terminal T80/50 for an open circuit or a short to Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring and the voltage supply was OK:

- Replace the Glow Plug Relay (J52).

- Perform a road test to verify repair.

If the fault does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

- End diagnosis.

If the fault does return and no malfunction is detected in the wiring and the voltage supply was OK:

- Replace the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Assembly is performed in the reverse of the removal.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

End diagnosis.