Electronic Controller/Glow Plug Relay

The electronic controller/glow plug relay is mounted at rear of left cylinder head. It monitors and controls glow plug operation. Four pins are used by the controller to determine glow plug operating requirements. Pin "B" senses voltage at the starter motor solenoid. Pin "C" senses glow plug voltage. Pin "D" supplies 12 volts, through the cold advance relay, to operate the controller when coolant temperature is below 80°F (27°C). Pin "E" is the controller ground.

A normally operating system works as follows: at room temperature and with ignition on and engine off, the glow plugs come on for 4-6 seconds and then go off for about 4.5 seconds. The glow plugs then cycle on for about 1.5 seconds and off for about 4.5 seconds, for a total start sequence of about 20 seconds. If the engine is cranked during or after start sequence, the glow plugs will cycle on and off for a total of 25 seconds after the ignition switch is returned from the crank position, whether engine starts or not.