Circuit/System Description
WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
When the S3 Transmission Shift lever is in the park position the B81B Park Position Switch is closed, when this occurs the reference voltage supplied by the K9 Body Control Module to circuit 5905 is pulled low through the B81B Park Position Switch by ground circuit 2851. The K9 Body Control Module compares the circuit 5905 Park Position Switch signal to the K71 Transmission Control Module Transmission Park input signal to determine if the park switch is the correct position.