Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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. Controller uses four pins to determine glow plug operating requirements. Pin "B" senses voltage at starter motor solenoid. Pin "C" senses glow plug voltage. Pin "D" supplies 12 volts, through cold advance relay, to operate controller when coolant temperature is less than 80°F (27°C). Pin "E" is 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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.