Glow Plug System: Description and Operation

Glow Plug System

System Overview

The 6.7L diesel engine uses a glow plug system that provides a heat source for combustion to improve cold engine starting and operation.

Component List

The system consists of the following components:

- Glow plugs
- Glow Plug Control Module (GPCM)

System Components

Glow Plugs

The glow plugs are located in the cylinder heads and preheat the air inside the combustion chamber to improve cold engine starting.

GPCM

The GPCM is located under the RH battery tray, behind the fender splash shield and controls glow plug operation. The GPCM is part of the On-Board Diagnostic (OBD) system and is designed to detect failures in the glow plug system.

Additionally, the GPCM controls and diagnoses the reductant heaters and relay. For additional information, refer to Engine Emission Control Engine Emission Control.

System Operation

The glow plug system is electronically controlled by the GPCM. If the coolant temperature is below 60°C (140°F), the GPCM energizes the glow plugs immediately after the key is placed in the ON position. Then, depending on the readings from the Engine Coolant Temperature (ECT) sensor, as well as the battery voltage, the GPCM determines how long the glow plugs are energized. The on time of the glow plugs is independent of the WAIT-TO-START lamp on time.