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.

Turn the ignition on.

With the scan tool, erase ECM DTCs.

Turn the ignition off for 10 seconds.

Turn the ignition on.

Monitor the scan tool for ECM DTCs.

Repeat this test several times.

Did this DTC set again?

Yes
1. Go To 2).
No
1. Refer to *INTERMITTENT DTC .
2) GROUND CIRCUIT OPEN

Fig 1: Checking Ground Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the Glow Plug Control Module harness connector.

Using a 12-volt test light connected to 12-volts, check the Ground circuit at the Glow Plug Control Module harness connector.

Does the test light illuminate brightly?

Yes
1. Go To 3).
No
1. Repair the Glow Plug Control Module Ground circuit for an open.
2. Perform ECM VERIFICATION TEST .
3) BATTERY SUPPLY CIRCUIT OPEN

Fig 2: Checking Battery Supply Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the Glow Plug Control Module harness connector.

Using a 12-volt test light connected to ground, check the Battery Supply circuit at the Glow Plug Control Module harness connector.

Does the test light illuminate brightly?

Yes
1. Replace the Glow Plug Control Module.
2. Perform ECM VERIFICATION TEST .
No
1. Repair the Glow Plug Control Module Battery Supply circuit for an open.
2. Perform ECM VERIFICATION TEST .