Backup Lamp: Description and Operation

BACKUP LAMPS

On a vehicle equipped with an automatic transmission, the backup lamps request signal is sent from the powertrain control module (PCM) to the body control module (BCM) via class 2. This signal is based on the state of the park neutral position (PNP) switch. On a manual transmission equipped vehicle, the B/U fuse in the engine wiring harness junction block supplies battery positive voltage to the normally open backup lamp switch. When the driver places the gear selector lever is in the REVERSE position, the backup lamp switch closes and the current flow is from the backup lamp switch to the BCM signaling for backup lamp illumination.

The BCM directly supplies voltage for backup lamp operation on both automatic and manual transmission vehicles. The backup lamps are grounded at G401 and G402 (G305 on vehicles that have the backup lamps located in the lower bumper facia).

For trailer wiring, a separate backup lamp circuit is connected through the TRLR B/U fuse to the trailer wiring harness.