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.
Section 5 (Body Control Modules): Description
The Body Control Module (BCM) controls many functions of the vehicle. These functions include A/C compressor request, A/C condenser fan, interior and exterior lighting, battery rundown protection, audible warnings (chime), instrument panel cluster indicators and gauges, electric door locks, low tire pressure monitor, and theft deterrent.
The BCM communicates with other systems over a serial data line to execute various vehicle functions. Communication between each system is accomplished by sending digitally coded messages, which consist of specific information the system module must follow. Each system module is assigned its own recognition code, so that it can respond to appropriate messages. The BCM acts as the power mode master, which can determine State Of Health (SOH) of other systems.
Other modules that communicate with the BCM over this line are the Electronic Brake Control Module (EBCM), Powertrain Control Module (PCM), Instrument Panel Cluster (IPC) and the remote control door lock receiver.
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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.