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.
Electric Rear Defogger
When the rear defog switch input circuit 292 to the body control module (BCM) is momentarily switched to ground, as when the rear defog switch is pressed, the BCM will respond by grounding circuit 193, the coil of the rear defog relay.
This action energizes the rear defog relay providing power to circuit 293-rear defog heater elements, circuit 683-heated mirror relay coil and circuit 683-rear defog LED. Momentarily switching circuit 292 to ground again will result in the BCM turning the rear defog relay OFF.
The first time in an ignition cycle that the rear defog is activated, the rear defog will remain ON or 15 minutes or until the ignition switch is turned OFF. If the rear defog is activated again during the same ignition cycle, the rear defog will remain ON for 7.5 minutes or until the ignition switch is turned OFF.
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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.