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) C60 C68
- Battery Voltage Signal
-
The scan tool displays the vehicle voltage.
- Rear Defog Relay Cmd.
-
The scan tool displays On/Off. When the rear window defogger switch is depressed, the body control module (BCM) energizes the Rear Window Defogger relay by suppling a B+ to the control circuit of the relay, when the scan tool displays as On.
- Rear Defog Switch
-
The scan tool displays Off /On. When the rear window defogger switch is depressed, the HVAC control module sends a message over Low Speed GMLAN to the BCM. When the switch is depressed the scan tool will display On.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.