Dimmable Backlighting
When the parking lamps are on, the Steering Column Control Module (SCCM) monitors the input from the instrument panel dimmer switch. The SCCM sends a message over the High Speed Controller Area Network (HS-CAN) to the Body Control Module (BCM) relaying the instrument panel dimmer switch input. Based on the input from the instrument panel dimmer switch, the BCM sends a voltage to the dimmable switches. The BCM sends a message over the HS-CAN to the Instrument Panel Cluster (IPC) and TBC module, and over the Medium Speed Controller Area Network (MS-CAN) to the Audio Front Control Module (ACM) (AM/FM/CD only), and HVAC module to indicate the backlighting intensity level.
If the receiving module receives invalid backlighting data from the BCM for 5 seconds or less, the receiving module defaults the backlighting to the last setting. If the receiving module does not receive the backlighting status message from the BCM or if the data received is deemed invalid for more than 5 seconds, the receiving module sets a missing message related DTC in continuous memory and defaults the backlighting to full nighttime intensity.