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.
Electrical System Diagnosis
Perform this diagnostic procedure if engine does not start when cold. "GLOW PLUGS" lamp may or may not come on. Check fuel system to ensure it is okay. Ensure battery voltage is 12.4 volts or more with ignition switch off. Check that cranking speed is at least 100 RPM.
- Connect 12-volt test lamp to ground. Place test lamp probe on battery stud (single Red wire) on glow plug controller. If test lamp lights, go to next step. If test lamp does not light, locate and repair open circuit between battery and glow plug controller.
- With ignition off, place test lamp probe on glow plug feed stud (2 Orange or Red wires) on glow plug controller. If test lamp lights, relay contacts are shorted. Replace glow plug controller and all glow plugs. If test lamp does not light, go to next step.
- Disconnect harness from all glow plugs. Connect test lamp to battery (12-volt source) and touch each glow plug terminal. Test lamp should light. Replace glow plug(s) if lamp does not light. Connect all glow plugs before going on to next step.
- With ignition switch in "RUN" position, connect 12-volt test lamp to ground. Remove controller connector and check voltage (from ignition switch) at terminal "D" of harness connector.
- If test lamp does not light, repair open circuit from ignition switch to controller. If test lamp lights, connect test lamp to battery (12-volt source) and check for ground at terminal "E" of harness connector.
- If test lamp does not light, repair open in ground wire to terminal "E" of connector. If test lamp lights, connect test lamp to battery (12-volt source) and check terminal "C" of harness connector.
- If test lamp lights, replace glow plug controller. If test lamp does not light, remove temperature inhibit switch connector and check for continuity through switch.
- Switch should be open above 125°F (52°C). If continuity exists, repair open circuit in harness, between glow plugs and terminal "C" of harness connector. If no continuity exists, replace inhibit switch.
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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.