Dimmable Backlighting

When the parking lamps are on, the SJB monitors the input from the instrument panel dimmer switch. The SJB sends a Pulse Width Modulated (PWM) voltage to the dimmable switches based on input received from the instrument panel dimmer switch.

The SJB also sends a message over the Controller Area Network (CAN) to the Front Controls Interface Module (FCIM), the Front Display Interface Module (FDIM) (vehicles without navigation), the HVAC module (vehicles without navigation), the Audio Control Module (ACM) and the Instrument Panel Cluster (IPC) to indicate the backlighting intensity level. If the receiving module receives invalid backlighting data from the SJB 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 SJB or if the data received is deemed invalid for more than 5 seconds, the receiving module sets DTC U0140 or U0140:00 in continuous memory (except the HVAC module (vehicles without navigation)) and defaults the backlighting to full nighttime intensity.