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)
The BCM controls various systems by monitoring inputs from switches, sensors and network messages from other modules. Based on these inputs received, the BCM activates outputs. For example, the BCM monitors the headlamp switch position and based on this input, the BCM may provide voltage to turn the exterior lamps on.
The BCM controls the following:
- Battery load shed function
- Battery saver function
- Brake shift interlock
- Delayed accessory function
- Dimmable backlighting
- Exterior lighting
- Heated rear window
- Heated exterior mirrors
- Horn
- Ignition state messaging
- Interior lighting
- Keyless entry keypad
- PATS
- Post crash alert function
- Power door locks
- Push-button start function (if equipped)
- RKE system
- Remote start function (if equipped)
- Theft alarm system
- TPMS
- Transport mode function
- Wipers and washers
Refer to the appropriate service information for descriptions of these systems.
Use the Manual With the Right Hardware
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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.