Theory Of Operation

When the Transmission Shifter is in the REVERSE position, the Powertrain Control Module (PCM) sends a CAN Bus message to Body Control Module (BCM) requesting Backup Lamp illumination. The BCM then provides a voltage output, through the Backup Lamp Feed circuit, to the Left and Right Backup Lamps. A ground path is provided to the Backup Lamps through the wiring harness to the body sheet metal.