P1648-GLOW PLUG MODULE INTERNAL FAULT

For a complete wiring diagram Refer to Section 8W

Possible Causes

BATTERY SUPPLY CIRCUIT OPEN

GROUND CIRCUIT OPEN

INTERMITTENT CONDITION

GLOW PLUG CONTROL MODULE

Diagnostic Test

1.CHECK FOR ACTIVE DTC

NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.

NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.

Did this DTC set again?

Yes

Go To2

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

2.GROUND CIRCUIT OPEN

Does the test light illuminate brightly?

Yes

Go To3

Repair the Glow Plug Control Module Ground circuit for an open.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

3.BATTERY SUPPLY CIRCUIT OPEN

Does the test light illuminate brightly?

Yes

Replace the Glow Plug Control Module.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Repair the Glow Plug Control Module Battery Supply circuit for an open.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).