P1649-GLOW PLUG MODULE POWER SUPPLY CIRCUIT
For a complete wiring diagram Refer to Section 8W
- When Monitored:
With the ignition on.
- Set Condition:
The Glow Plug Control Module reports a power supply circuit fault to the ECM.
| Possible Causes |
| INTERMITTENT DTC |
| (K344) FUSED MAIN RELAY OUTPUT CIRCUIT OPEN OR HIGH RESISTANCE |
| (A29) FUSED B+ CIRCUIT OPEN OR HIGH RESISTANCE |
| (Z924) GROUND CIRCUIT OPEN OR HIGH RESISTANCE |
| GLOW PLUG MODULE |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1. DTC IS ACTIVENOTE: Diagnose and repair any system voltage or Main 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. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
2. (K344) FUSED MAIN 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 (K344) Fused Main 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 (K344) Fused Main Relay Output circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
3. (A29) FUSED B+ CIRCUIT OPEN OR HIGH RESISTANCE
Turn the ignition off.
Using a 12 volt test light connected to ground, check the (A29) Fused B+ 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 (A29) Fused B+ circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
4. (Z924) GROUND CIRCUIT OPEN OR HIGH RESISTANCE
Using a 12 volt test light connected to B+, check the (Z924) 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
- Replace the Glow Plug Module in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Repair the (Z924) Ground circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)