Interior Lighting Systems Description and Operation

Interior Lighting Systems Description and Operation

Interior Lamps

The interior lamps consist of two groups. The first group are those lamps which may not be dimmed. The second group include lamps that may be dimmed.

Courtesy/Illuminated Entry Lamps

These lamps may be manually turned on by placing the interior lamp switch in the ON position, or by opening a door.

* The Dome Lamp
* The Rear Compartment Courtesy Lamp
* The Rear View Mirror Map Lights

The inadvertent power control circuit of the BCM supplies battery positive voltage to the dome lamp and the map lamps. When any door is opened, the door jamb switch contacts close providing a door open input to the BCM. The BCM then provides a ground to the interior lamps. The interior lamps receive a ground at G401 or G403.

If the driver inadvertently leaves any interior lamp on the BCM will turn it off after a 20 minute time-out.

The courtesy lamps will normally turn off using the theater dimming feature. The BCM provides a pulse width modulated ground to the interior lamps for the theater dimming feature. The courtesy lamps will also turn off immediately if a door lock command is received with all the doors closed, or if the ignition switch is turned to the ON position.

Keyless Entry Interior Illumination

When the body control module (BCM) receives a door unlock command from the remote keyless entry (RKE) transmitter, the BCM will keep the courtesy lamps on approximately 20 seconds and then turn them off through the theater dimming feature. If the door locks are activated to the LOCK position, the courtesy lamps will deactivate immediately. When the ignition switch is turned to the ON position the courtesy lamps will deactivate in approximately one second.

Rear Compartment Lamp

The inadvertent power control circuit also provides battery positive voltage to the rear compartment courtesy lamp. When the rear compartment is opened, its switch closes and the rear compartment lamp illuminates. The rear compartment lamp is grounded at G403.

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.

* HVAC control head assembly
* Radio
* The instrument panel cluster (IPC)
* Various switches

When the ignition switch is turned to the ON position, the vacuum fluorescent (VF) display (radio) turns on at maximum brightness. When the park lamps are ON all incandescent back lighting turn ON at the dimming level indicated by the IP dimmer switch. At the same time all vacuum fluorescent (VF) displays dim to match the indicated dimming level. When the headlamp switch is placed in the PARK position, the park lamp supply voltage circuit provides an input to the body control module (BCM). The BCM then supplies voltage to the instrument panel dimmer switch through the instrument panel dimming lamps control circuit. The setting of the instrument panel dimmer switch determines the amount of voltage that the instrument panel dimmer switch supplies to the BCM through the instrument panel dimming lamps low reference circuit. The BCM then sends a pulse width modulated (PWM) voltage to all the interior lamps. All the vacuum florescent (VF) and incandescent back lighting lamps are provided a specific voltage and are then grounded. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting turn on at the dimming level indicated by the IP dimmer switch. When the IP dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from Minimum intensity to maximum brightness in response to the IP dimmer switch.

Inadvertent Power

The body control module used in this vehicle controls the lighting system through circuits that enable the interior lamps. The BCM opens these enabling circuits shortly after the ignition switch is turned OFF with no lamp switch activity. If the ignition switch is turned to any position other than OFF, or if a lamp switch is activated during this period, the timer will reset itself again.