Switch, Backup Lamp: Operation

The backup lamp switch controls a path to ground for the Powertrain Control Module (PCM) on the reverse switch signal circuit. The PCM reads this input through an internal pull-up, then sends an electronic reverse switch status  message to the Body Control Module (BCM) over the Controller Area Network (CAN) data bus network. The BCM controls an output through a high side driver that regulates the flow of battery current to the backup lamp bulbs as appropriate on the backup lamp feed circuit.

The backup lamp switch plunger is mechanically actuated by the gearshift mechanism within the transmission, which will depress the switch plunger and close the switch contacts whenever the (R  ) Reverse gear has been selected. The switch has a path to ground at all times through a take out and eyelet terminal of the engine wire harness that is secured to the body sheet metal.

The backup lamp switch as well as the hardwired inputs and outputs of the switch may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information.