Glow Plug Control Unit Faulty

2257-GLOW PLUG CONTROL UNIT FAULTY





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on and the Glow Plugs commanded on.

- Set Condition:
The Glow Plug Control Module reports a power supply circuit fault to the ECM.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE
NOTE: Diagnose and repair any system voltage or Main/ECM Relay DTCs before continuing with this test.

Ignition on, engine not running.
With the scan tool, Clear DTCs in the Engine Control Module (ECM).
With the scan tool, actuate the Glow Plugs.
Monitor the scan tool for at least two minutes.
With the scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go To 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Component Tests and General Diagnostics

2. FUSED ASD RELAY OUTPUT CIRCUIT OPEN OR HIGH RESISTANCE
Turn the ignition off.
Disconnect the Glow Plug Module harness connector.
Turn the ignition on.
Using a 12 volt test light connected to ground, check the Fused ASD Relay Output circuit in the Glow Plug Module harness connector.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

- Go to 3

No

- Repair the Fused ASD Relay Output circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. Verification Tests

3. GROUND CIRCUIT OPEN OR HIGH RESISTANCE
Turn the ignition off.
Using a 12 volt test light connected to B+, check the Ground circuit in the Glow Plug Module harness connector.

NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

- Go to 4

No

- Repair the Ground circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. Verification Tests

4. GLOW PLUG MODULE
Replace the Glow Plug Module.
Turn the ignition on.
With the scan tool, Clear DTCs.
With the scan tool, actuate the Glow Plugs.
Monitor the scan tool for at least two minutes.
With the scan tool, select View DTCs.
Is the status Active for this DTC?

Yes

- Go to 5

No

- Test Complete.
- Perform the ECM Verification Test Ver. 1. Verification Tests

5. ENGINE CONTROL MODULE (ECM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Glow Plug Module and the Engine Control Module (ECM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the ECM Verification Test Ver. 1. Verification Tests

No

- Replace the Engine Control Module (ECM).
- Perform the ECM Verification Test Ver. 1. Verification Tests