Backup Lamps

WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

The backup (or reverse) lamps have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured to the body sheet metal within the passenger compartment. The Powertrain Control Module (PCM) continually monitors a hard wired multiplex input from the Transmission Range Sensor (TRS), then sends the appropriate electronic transmission gear selector status messages to other electronic modules over the CAN data bus. Whenever the ignition switch is in the ON position and the Body Control Module (BCM) (also known as the Common Body Controller/CBC) receives an electronic message indicating the status of the transmission gear selector is REVERSE, it provides a battery voltage output to the backup lamps on the backup lamp control output circuit.