Glow Plug System: Description and Operation

Glow Plug System

Glow Plug Control Module





The 6.0L diesel engine uses a glow plug system that preheats air in the combustion chamber to improve cold engine starting.

The glow plug system consists of the following components:

- Glow plugs
- Glow plug control module
- PCM
- Engine Oil Temperature (EOT) sensor
- Barometric Pressure (BARO) sensor

The glow plug monitor system is part of the On-Board Diagnostic (OBD) System.

The glow plug system is electronically controlled by the PCM. If the oil temperature is below 55°C (131°F), the PCM will energize the glow plugs immediately after the key is placed in the ON position. Then, depending on the readings from the EOT sensor and the BARO sensor, the PCM determines how long the glow plugs will be on.


Glow Plugs - PCM-Controlled





The glow plugs are located in the cylinder heads, under the glow plug wiring harness.

The glow plugs are self-regulating. If the engine oil temperature is above 55°C (131°F), the PCM will bulb-check the WAIT TO START lamp but not energize the glow plug relay.

The glow plug ON time varies from 0-120 seconds depending on battery voltage, engine oil temperature and barometric pressure.

The glow plug ON time is independent of the wait to start lamp ON time.

The glow plug control monitor system is designed to find failed glow plugs or failed wiring in the glow plug system.