Glow Plug System: Testing and Inspection

Glow plug system wiring schematic:

Glow plug system diagnosis:

SYSTEM DIAGNOSIS
The glow plug relays are automatically controlled. Do not attempt to bypass the relay terminals of the controller, as the glow plugs will be damaged.
1. Inspect all system electrical connectors and ensure terminals are free from corrosion and that connectors are fully seated.
2. Inspect engine harness ground stud, ensuring wire end terminals are free from corrosion and that stud nut is properly tightened.
3. Inspect relay terminal lugs on controller, ensuring wire end terminals are free from corrosion and nut is tighten to specification.
4. If glow plugs function normally but glow plug lamp fails to light, inspect connections and bulb in instrument panel jumper harness and repair as needed.
5. If system fails to operate properly refer to wiring schematic and diagnostic charts, Figs. 3 and 4.