Common Symptoms
- Hard starting or extended cranking in cold weather
- White or gray smoke on cold start
- Engine runs rough until warmed up
- Check engine light illuminated
- Glow plug indicator light remains on or flashes
Most Likely Root Causes
- Failed glow plug control module or relay
- Open or shorted wiring to glow plug module
- Corroded or loose electrical connections at module
- Failed individual glow plugs causing module feedback fault
- ECM internal fault in glow plug control circuit
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Component Location
Glow plug control module is typically mounted on the engine block, cylinder head area, or firewall near the diesel fuel system.
Manufacturer Notes
Some diesel engines use individual glow plug control while others use a centralized module that cycles all glow plugs simultaneously.
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