The Body Control Module (BCM) is the central organizational element of your car that controls other security systems of the vehicle. Typically in a car the BCM controls the power windows, power mirrors, air conditioning, immobilizer system, central locking, etc. A BCM is defined as a computer component in a vehicle that operates, regulates and checks the vehicle's electronic devices. BCMs are designed to make a car's operations simpler by controlling all electrical operations in one module. It essentially functions as the main computer for many of the vehicle’s engine performance and drivability functions.