Glow Plug System: Description and Operation

The glow plug system is used to assist in providing the heat required to begin combustion during engine starting at cold ambient temperatures.

The glow plug relay switches power to the glow plugs and is commanded on and off by the PCM. The glow plugs are heated before and during cranking, as well as initial engine operation. The PCM monitors the glow plug relay output voltage which indicates if the relay is following the PCM commands.