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.
The A26 Heater and Air Conditioning User Interface Control - Front communicates with the K9 Body Control Module via serial data. When the BCM receives an abnormal switch signal voltage message from the user interface control, the BCM sets the DTC.