Interior Lamps Dimming

The second group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination and incandescent lamps.

When the ignition switch is turned to the RUN position, the radio's VF displays turn on at maximum brightness. When the park lamps are on, all incandescent back lighting turns on at the dimming level indicated by the instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the body control module (BCM). When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all incandescent back lighting, respond from minimum intensity to maximum brightness in response to the I/P dimmer switch. The following switches and components have back lighting when the park lamps are on.

• The instrument panel cluster (IPC)
• The radio
• The window and heated seat switches
• The garage door opener switch
• The sunroof switch
• The HVAC control assemblies
• The headlamp and panel dimmer switch
• The tow/haul switch
• The transfer case shift control switch
• The height control switch
• The PSIR disable switch
• The PRNDL lamps
• The traction control switch
• The steering wheel control switches
• The rear wiper/washer switch

The left and right front door switch illumination is controlled, receives voltage and ground from the drivers door module (DDM) and the passenger door module (PDM), respectively. The radio is also a class II module and has full control of its illumination. The BCM, DDM, PDM, and radio communicate through class II serial data for the lamp illumination commands.

The I/P cluster illumination lamps receive voltage and are controlled by the BCM on the instrument panel lamps dimming supply voltage circuit. Ground for the instrument panel lamps is at G203.

The various switches, HVAC control assembly, and the PRNDL lamps receive voltage, and are controlled by the BCM on the instrument panel lamps dimming control circuit. Ground for the rear window switches is at G302 and G306. Ground for the traction control switch, steering wheel controls, and the rear window/wiper switch is at G200. Ground for the remaining switches is at G203.

The following indicators receive voltage from the BCM and are controlled by various modules.

• The traction control switch traction control OFF indicator
• The height control switch high clearance indicator
• The transfer case control switch 4WD position indicator
• The heated seat indicators

The indicators receive voltage from the BCM on the LED dimming circuit. Ground/control for the indicators is from the various modules. The modules controlling the above indicators are as follows:

• The electronic brake control module (EBCM)
• The air suspension module
• The driver door module (DDM)
• The passenger door module (BCM)