Glow Plug Control Module Control Circuit
On many diesels, a dedicated module controls the glow plugs that help with cold starts.
What the car has detected
The engine ECU detects an electrical fault in the glow plug module circuit: an open circuit or a short to ground or to voltage.
When cold it may be hard to start, or not start at all. It is not usually dangerous, but fix it before winter.
Symptoms
- Engine warning light on
- The glow plug light does not come on or goes out quickly
- Longer or harder starting
Possible causes
- Faulty glow plug module
- Damaged or corroded connector or wiring
- Short circuit in a glow plug or its wire
Checks for the garage
- Check the glow plug module connector for corrosion or loose pins
- Activate the glow plug module with the diagnostic tool
- Measure the resistance of each glow plug
Next step
Ask them to check the glow plug module, its connector and wiring, and the glow plugs themselves.
It can wait if the car starts well, but fix it before the cold comes.