Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Glow Plug Monitor
The 6.0L diesel engine uses a glow plug monitor system designed to detect failed glow plugs or failed wiring in the glow plug system. 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 failure. The glow plugs are not operated during this test.
The glow plug monitor self-test is a functional KOER test of the 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.
The following is an example of some of the input and output components monitored by the PCM. The components monitored belong to the engine system.
- The input components monitored by the PCM are the engine oil temperature (EOT) and the barometric pressure (BARO) sensor.
- The output component monitored by the PCM is the GPCM.
- The MIL is activated after a concern if the concern detected affects emissions.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.