Glow Plug Monitor

Glow Plug Monitor

Glow Plug System:

The diesel engine utilizes a Glow Plug Monitor (GPM) system designed to detect failed glow plugs or failed wiring in the glow plug system. Diagnostic Trouble Codes (DTCs) indicate which cylinder has failed glow plugs or failed glow plug wiring.

The glow plug system is composed of a solid state Glow Plug Control Module (GPCM), glow plugs and the associated wiring harness. The glow plug on-time is controlled by the Powertrain Control Module (PCM) and is a function of oil temperature, barometric pressure and battery voltage. The PCM enables the GPCM which drives the individual glow plugs. Glow plug on-time, varies between 1 to 120 seconds. In addition to the PCM control, the GPCM limits the glow plug operation to 180 seconds regardless of PCM commanded on-time. The power to the glow plugs is provided through the GPCM solid state drivers directly from the vehicle battery. The GPCM monitors and detects individual glow plug functionality, and the control and communication links to the PCM. The failures detected by the GPCM are passed to the PCM using a serial communication signal on the diagnostic line.

NOTE: Wait to start lamp on time is independent from GPCM on time.

The Key On Engine Off (KOEO) test is performed in order to test the GPCM control circuit for failure. 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) performed on demand with the engine running and the A/C off. The PCM will activate the GPCM which monitors the glow plugs. The pedal may be used to increase the engine speed to increase voltage if needed. A fault must be present at the time of testing for the test to detect a fault. The DTCs will be sent to the PCM on the diagnostic line and outputted to the scan tool.

Glow Plug Monitor:

The following is an example of some of the input and output components monitored by the GP monitor. The components monitored belong to the engine system.
1. Inputs:
Engine Oil Temperature, Barometric Pressure Sensor (BARO),...
2. Outputs:
Glow Plug Control Module (GPCM)
3. The MIL is activated after a fault, if the fault detected affects emissions.