Dimmable Backlighting

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

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 components and 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 Audio Control Module (ACM), the HVAC module and the Instrument Cluster (IC) 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 a missing message related DTC in continuous memory (except the HVAC module) and defaults the backlighting to full intensity.