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.
Body Control Module (BCM)
- A/C Switch
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The scan tool displays On or Off. The BCM displays On when it receives an input from the HVAC control head indicator an A/C request.
- Battery 1
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The scan tool displays the value of the vehicle battery voltage.
- Rear Defog Relay
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The scan tool displays On or Off. When the BCM energizes the Rear Defogger relay, the scan tool will display On. When the BCM de-energizes the Rear Defogger relay, the scan tool will display Off.
- Rear Defog Switch Input
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The scan tool displays On or Off. When you depress the rear window defogger switch, the switch pulls the rear defogger switch signal circuit of the BCM low. The scan tool will display On. When you depress the switch again, the rear defogger switch signal circuit of the BCM will return to its normal state. The scan tool will display Off.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.
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