The brake pedal position sensor receives a low reference signal and a 5-volt reference signal from the BCM. Whenever the brake pedal is applied, the brake pedal position sensor applies a variable voltage signal to the BCM through the stop lamp switch signal circuit. Brake pedal position sensor calibration must be performed after the brake pedal position sensor or body control module (BCM) have been serviced. The calibration procedure will set brake pedal position sensor home value. This value is used by the BCM to determine the action of the driver applying the brake system and to provide this information to the vehicle subsystems via the class 2 communication bus.