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.
Rear Window Defrost
When the rear window defrost switch is activated, the BCM activates the rear window defrost relay (located in the BJB). When the rear window defrost is activated from the switch, the rear window defrost grid is energized and the BCM supplies voltage to illuminate the rear window defrost switch status LED. The rear window defrost system may also be automatically activated as an extra load for accelerated engine warm-up, however the defrost switch status LED remains off unless the defrost switch is activated.
The BCM deactivates the rear window defrost relay when one of these conditions is met:
- The rear window defrost switch is pressed when the feature is active.
- Ignition state is changed from ON to OFF.
- A predetermined timer completes.
- Battery voltage has dropped below a specified threshold (load management strategy).
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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.