Backup Lamp: Description and Operation

Backup Lamp Circuit Description

If the ignition switch is in RUN or START position, voltage applies through the B/U AND IGN3 circuit breaker to the backup lamp switch. Whenever the gear selector lever shifts to REVERSE, the backup lamp switch closes and voltage applies to the backup lamps. The backup lamps remain lit as long as the backup lamp switch is closed.

If the vehicle is equipped with a MD automatic transmission, the transmission control module signals the TCM interface module when the transmission is shifted into Reverse. The TCM interface module, in turn, applies an output signal to the backup lamps.