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.
Circuit/System Description
Battery positive voltage is supplied through the REAR DEFOG fuse located in the right rear fuse block to the REAR DEFOG relay switch input. When the rear window defogger switch is depressed, the HVAC control module sends a message via serial data message to the rear integration module (RIM) to enable the rear window defogger. The RIM energizes the REAR DEFOG relay by grounding the rear defog relay control circuit. This allows battery voltage from the relay switch input through the switch contacts and out the relay switch output to the rear window defogger. The RIM then sends a message via serial data message to the HVAC control module requesting the illumination of the rear window defogger indicator.
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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.