Glow Plug Monitor

GLOW PLUG MONITOR

The glow plug monitor system is designed to detect glow plug or wiring concerns in the glow plug system. Diagnostic trouble codes (DTCs) indicate which cylinder has failed glow plugs or failed glow plug wiring.

The key on engine off (KOEO) test is carried out in order to test the glow plug control module (GPCM) control circuit for concern. The glow plugs are not operated during this test.

The glow plug monitor self-test is a functional KOER test of the powertrain control module (PCM) carried out on demand with the engine running and the A/C off. The PCM activates the GPCM which monitors the glow plugs. The accelerator pedal may be used to increase the engine speed to increase voltage if needed. A concern must be present at the time of testing for the test to detect a concern. The DTCs are sent to the PCM on the diagnostic line and output to the scan tool.

DTC P0670: The test diagnoses the glow plug module control circuit between the GPCM and the PCM. The glow plug module control circuit check runs for 5 seconds. During that check the glow plug module control circuit is checked for open or short circuit condition.

DTC P0684: The test diagnoses the glow plug module diagnostic communication circuit between the GPCM and the PCM. The glow plug module diagnostic communication circuit check runs for 10 seconds. During that check the GPCM sends a glow plug status information to the PCM through the diagnostic communication circuit. The PCM checks the glow plug status for out of range low and out of range high voltages.

DTCs P0671 through P0688: The glow plug check runs for 8.5 seconds. During that check the PCM monitors each glow plug for an open or short circuit condition by measuring current.

DTC P0381: The glow plug/heater indicator circuit check runs when controller area network (CAN) is operational and has no errors. The typical monitoring duration for this monitor is 5 seconds. During that check the PCM monitors the CAN for the wait-to-start indicator ON message from the instrument cluster. When the DTC P0381 is set it indicates a concern with the CAN or with the wait-to-start indicator and not the concern with the glow plug wiring or glow plugs.