Circuit/System Description

WARNING: This page is about a different car, the 2020 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

With the engine running and the transmission in the reverse position, the transmission control module (TCM) sends a serial data message to multiple control modules. The BCM recieves a serial data message from the TCM when the transmission is placed in the reverse position. The BCM responds sending a serial data message to the Lighting Control Module indicating that the gear selector is in the reverse position. The Lighting Control Module responds by applying battery voltage through the backup lamps control circuit illuminating the backup lamps. Applied voltage is also sent through the backup lamps control circuit to the A11 Radio and A10 Inside Rearview Mirror (if equipped with RPOs DD8/DRZ). The A11 Radio monitors this input to turn on the rearview camera display. The A10 Inside Rearview Mirror monitors this input to turn on the rearview camera display if equipped with RPO DRZ. If equipped with RPO DD8, the A10 Rearview Mirror monitors this input to disable the automatic day-night feature. Once the driver moves the gear selector out of the reverse position, a serial data message is sent from the TCM to the BCM. The BCM responds by sending a serial data message to the Lighting Control Module, the message indicates that the gear selector is no longer in the reverse position. The Lighting Control Module responds by removing battery voltage from the backup lamps control circuit. The engine must be running for the backup lamps to operate.