Glow Plugs

Fig 1: Glow Plug System Diagnosis (C/K, R/V, G, P)

Glow plugs are threaded into each cylinder's combustion chamber. Glow plugs are small heaters that assist in cold starting. The glow plug controller/relay (mounted on top-rear of engine) cycles 12 volts to these 6-volt heaters, which causes them to heat rapidly. After the engine starts, glow plugs continue to cycle on and off for about 25 seconds, depending on coolant temperature.