Brake Lamps

Each combined brake lamp / rear turn signal Light Emitting Diode (LED) unit and the Center High Mounted Stop Lamp (CHMSL) have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured by a ground screw to the body sheet metal within the passenger compartment. The Antilock Brake System (ABS) module monitors a hardwired input from the brake pedal position sensor, which is actuated by movement of the brake pedal arm. When the ABS module receives an input from the brake pedal position sensor indicating movement of the brake pedal arm, it responds by sending the appropriate electronic brake lamp switch  status message to the BCM over the CAN data bus. The BCM then controls brake lamp and CHMSL illumination through High Side Drivers (HSD) on the left and right brake lamp control circuits. When the turn signals are active, the signal takes precedence over the brake lamp.