Fuel Delivery and Air Induction: Description and Operation

Fig. 1 Glow plug system wiring diagram. 1983:

Fig. 2 Glow plug system wiring diagram. 1984---86:

Fig. 3 Glow plug system wiring diagram. 1987:

The glow plug fast start system controls glow plug operation according to various operating conditions. When the ignition switch is turned on, the control switch is energized, which, in turn, energizes the power relay. The power relay contacts close and battery current is directed to the glow plugs. When the glow plugs reach a predetermined temperature, current to the plugs and the wait lamp is cut off. At this time, the engine can be started. After the engine is started, the glow plugs will cycle on and off for 40---90 seconds. This cycling of the glow plugs helps to eliminate start up exhaust smoke.
A control switch, threaded into the cylinder head coolant jacket, senses engine coolant temperature. When restarting a warm engine, the glow plug system will not be activated unless the coolant temperature falls below normal operating temperature.
Refer to Figs. 1, 2 and 3 for glow plug system troubleshooting procedures.