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 Functions
Body Control Module (BCM) performs multiple body control functions. BCM can control devices directly connected to its outputs based on input information obtained from two sources:
- Sensors and switches that are directly connected to BCM.
- Information received from other vehicle systems connected to class 2 serial data link.
BCM evaluates this information and controls certain body control systems by commanding outputs on or off.
BCM is also capable of controlling other vehicle systems that are not directly wired to BCM. BCM does this by sending specific messages on class 2 serial data link. Vehicle system capable of performing a required function will respond to BCM message.
BCM controls following functions:
- Audible warnings.
- Interior lighting.
- Automatic door locks.
- Automatic headlight control.
- Keyless entry (if equipped).
- Passlock theft deterrent.
- Content theft deterrent.
- Retained Accessory Power (RAP).
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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.