Interior Lamps Dimming

The third group includes the following lamps which may be dimmed. This group may use a combination of Vacuum Fluorescent (VF) illumination and of incandescent lamps.
^ The left and right window switches
^ The Climate Control Panel (CCP)
^ The rear blower switch
^ The Radio (IRC)
^ The Instrument Panel Cluster (IPC)
^ The headlamp switch assembly
^ The front and rear ashtray lamps
^ The shift indicator lamp
^ The Driver Information Center (DIC) switches
^ The heated seat switches
^ The steering wheel controls

Dimming of the interior lighting systems is as follows:
^ Ignition Off
- Parking lamps on: The dimmer switch will control the incandescent lamps, while the vacuum florescent will remain off.
- Parking lamps off: All displays and panel lamps are OFF.

^ Ignition On
- Parking lamps on: All displays and panel lamps will dim, unless the twilight photocell indicates daylight.
- Parking lamps off: Full brightness of all displays, including vacuum efflorescence.

^ Accessory Power
- Parking lamps on: All incandescent lamps and the radio display are controlled by the dimming switch. The radio display will be full brightness if the twilight photocell indicates daylight.
- Parking lamps off: Only the radio display comes on at full brightness.

The instrument cluster controls all of the interior dimming functions. The instrument cluster receives an ambient light level input from the ambient light sensor and determines whether it is light or dark. If the ambient light sensor is inoperative, the instrument cluster will assume a condition of darkness. Dimming of the VF displays is only allowed when the ignition switch is in the RUN position, the park lamps are on, and the ambient light sensor indicates darkness. If all conditions for the VF dimming are met, the instrument cluster uses the input from the potentiometer in the headlamp switch to determine the level of dimming. The dimming level is sent to the radio (IRC), the cellular telephone (PHN), and the Climate Control Panel (CCP) by a Class 2 message.

These modules then adjust the dimming level of their VF display. The instrument cluster provides dimming control of the incandescent lighting through the INC DIM 1 and INC DIM 2 outputs. The instrument cluster provides dimming control of the electronic PRNDL LED through the LED dimming signal circuit. The dimming level will vary based on the potentiometer in the headlamp switch when the park lamps are on and the ambient light sensor indicates darkness, regardless of the position of the ignition switch.