Glow Plugs

Glow plugs are threaded into each cylinder combustion chamber. Glow plugs are small heaters that assist in cold starting. The glow plug controller and relay cycle 12 volts to these 6 volt heaters, which causes them to heat rapidly. After the engine starts, the glow plugs remain on for short time then shut off.

Controller failure, as in the case of prolonged preheat (more than 9 seconds of initial glow plug activation), would cause a circuit breaker to open in the controller. When this takes place, glow plug circuit fails to operate completely.