Principles of Operation

Instrument Cluster and Panel Illumination

Principles of Operation

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

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 voltage to the dimmable switches and control components based on input received from the instrument panel dimmer switch. The SJB also sends a message over the Medium Speed Controller Area Network (MS-CAN) to the HVAC module (if equipped with automatic temperature control), the Audio Control Module (ACM), and the Instrument Cluster (IC) to indicate the backlighting intensity level.

Non-Dimmable Backlighting

When the ignition switch is in the START or RUN positions, the delayed accessory relay provides voltage from the SJB to the non-dimmable components.