Principles of Operation
Dimmable Backlighting
The lighting control module (LCM) generates a variable pulse-width modulated (PWM) voltage which is distributed to the dimmable components when the parking lamps are on. Light intensity is adjusted by rotating the instrument panel dimmer switch. The dimmable backlighting components consist of:
- Adjustable pedal switch
- Audio unit
- Traction control switch
- Headlamp switch
- Message center switch
- Rear audio/climate control switch
- Clock
- Front cigar lighter
- RH rear cigar lighter
- LH rear cigar lighter
- Speed control switch
- Audio/climate control switch
The LCM communicates backlighting intensity signals on the standard corporate protocol (SCP) network to the following:
- Heating ventilation air conditioning (HVAC) module
- Overhead console
- Instrument cluster (IC)
If the headlamps are operated during daylight hours, the light sensor amplifier detects high ambient light levels and signals the LCM to keep illumination levels readable and therefore are non-adjustable on the following components:
- Audio unit
- HVAC
When the headlamp switch is in the OFF position, the IC internally powers the gauge illumination lamps to full brightness.
Fixed Level Backlighting
The following components have fixed level backlighting that is illuminated when the ignition switch is in the RUN or ACCESSORY position:
- Exterior mirror control switch
- Heated seat switches
- Driver window control switch
- Passenger window control switch
- RH rear window control switch
- LH rear window control switch
- Driver door lock control switch
- Passenger door lock control switch