Circuit/System Description
WARNING: This page is about a different car, the 2018 Cadillac XTS. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) communicates with the remote control door lock receiver through the keyless entry challenge active circuit. The challenge active signal is activated by the keyless entry control module and sent to the BCM when active communication between the vehicle and the keyless entry transmitter is initiated.