Principles of Operation

PRINCIPLES OF OPERATION

Dimmable Backlighting
When the parking lamps are on, the smart junction box (SJB) provides a pulse-width modulated (PWM) voltage to the dimmable instrument panel switches and components. The instrument panel dimmer switch allows the brightness level of the dimmable backlights and displays to be adjusted.

The SJB communicates with the instrument cluster through the controller area network (CAN). The instrument cluster then increases or decreases the intensity of the instrument cluster backlighting accordingly. The dimmable components consist of the:
- Instrument cluster
- Message center switch
- Hazard flasher switch
- Climate control assembly
- Transmission range (TR) indicator
- Convertible top switch (part of the overhead console) (if equipped)
- Steering wheel switches
- Headlamp switch

Non-Dimmable Backlighting
When the key is in the ACC or RUN positions, the SJB energizes the accessory delay relay, providing switched voltage to the non-dimmable components and switches. The non-dimmable components consist of the:
- Driver window control switch
- Passenger window control switch
- Driver door lock control switch
- Passenger door lock control switch

Fault Management
The dimmable backlighting defaults to full intensity if the instrument panel dimmer switch or circuitry fails.