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 16 (Body Control Modules): Description
The Body Control Module (BCM) communicates with the following systems over the serial data line to control various functions.
- Powertrain Control Module (PCM)
- Instrument Panel Cluster (IPC)
- Real Time Damping (RTD)
- Seat Control Module (SCM)
- Left Door Control Module (LDCM)
- Right Door Control Module (RDCM)
- Remote Function Actuator (RFA)
- Heating, Ventilation & Air Conditioning (HVAC)
- Radio
- Anti-lock Brake System (ABS)
- Supplemental Inflatable Restraint (SIR)
Some vehicle systems share data 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 and sends power mode messages on the serial data line. Power mode messages are ignition switch position. Systems not directly communicating with the ignition switch use the power mode messages to determine ignition switch position. Systems other than the BCM respond to the power mode messages with a State Of Health (SOH) code message. The SOH messages lets the BCM know that those systems can communicate with other systems.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.