Interior Lighting Systems Description and Operation

Interior Lighting Systems Description and Operation

Interior Lamps

The interior lighting consists of the dome lamp.

Dome Lamp

The DOME PANEL circuit breaker in the instrument panel (IP) fuse block supplies battery positive voltage to the dome lamp. A path to ground is provided for the dome lamp through the IP lamps dimmer switch or the door jamb switch. When the driver places the IP dimmer switch in the dome lamp ON position or opens the driver's door, the dome lamp will illuminate.

Interior Lamps Dimming

This group includes incandescent lamps which may be dimmed. The following lamps are part of this group:

* The ashtray lamp
* The HAZARD name plate
* The HVAC control head assembly
* The instrument panel cluster (IPC)
* The radio
* The seat belt alarm, if equipped
* The trailer marker lamps switch, if equipped
* The various transmission control switches

The DOME PANEL circuit breaker in the instrument panel (IP) fuse block supplies battery positive voltage to the headlamp switch. When the headlamp switch is placed in the PARK or HEADLAMP position, battery positive voltage is supplied to the IP dimmer switch. The IP dimmer switch has a variable resistor inside of it. The setting of the variable resistor will determine the amount of voltage drop across it. The IP dimmer switch then supplies voltage to splice 221. Splice 221 distributes the voltage to all of the lamps listed above. All of the lamps listed above, with the exception of the PRNDL indicator lamp, are grounded at G101 or G111. The PRNDL indicator lamp has a case ground.

Driver Controls and Modules

Driver controls include the following components.

* The hazard switch/hazard warning switch
* The headlamp dimmer switch
* The headlamp switch
* The IP dimmer switch
* The stop lamp switch
* The trailer marker lamps switch, if equipped
* The trailer stop lamp switch, if equipped
* The turn signal switch

There are three modules involved with the lighting system:

* The daytime running lights (DRL) control module
* The transmission control module (TCM)
* The transmission control module (TCM) interface module