Interior Lighting Systems Description and Operation

INTERIOR LIGHTING SYSTEMS DESCRIPTION AND OPERATION

INTERIOR LAMPS
The interior lamps consist of the following 2 groups. The first group are those lamps which may not be dimmed. The second group includes lamps that may be dimmed.

COURTESY/ILLUMINATED ENTRY LAMPS
This group includes lamps that may be manually turned ON by placing the interior lamp switch in the ON position, or by opening a door.
- The dome lamp
- The reading lamps
- The rearview mirror lamps
- The vanity mirror lamps

The dome lamp switch has 3 positions: DOOR, OFF, and ON. When in the DOOR position, the dome lamp operation is controlled by the body control module (BCM). The ON position provides a ground for continuous operation. Ground is provided at G302. The OFF position turns OFF any dome lamp operation. The courtesy lamps, may be manually turned ON by placing the instrument panel (I/P) dimmer switch in the DOME position. When the dome lamp switch is in the DOOR position, the dome lamp will illuminate when a door is opened. When a door is opened, the courtesy lamps turn ON. After all the doors have been closed, the courtesy lamps will remain illuminated approximately 10 seconds after the last door closes. When the driver places the dome lamp switch in the OFF position, the dome lamp will be disabled.

The inadvertent power control circuit of the BCM supplies battery positive voltage to the dome lamp, reading lamps, and vanity mirror lamps. When any door is opened, the door jam switch contacts close and the door open input to the BCM is grounded.

If the driver inadvertently leaves any interior lamp ON, the BCM will turn it OFF after 20 minutes.

The courtesy lamps will normally turn OFF using the theater dimming feature. The BCM provides a pulse width modulated ground to the dome lamp 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 driver uses the door key in order to unlock the doors, the body control module (BCM) receives a door unlock signal. The BCM must have inputs that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF, and all the doors are closed. The BCM will then activate the interior lamps. The courtesy lamps will remain ON, approximately 10 seconds after the door is closed. The BCM will then turn them OFF through the theater dimming feature. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the ON or START position, the courtesy lamps will turn OFF immediately.

On vehicles with a remote control door lock receiver (RCDLR), when the RCDLR module receives a door unlock command from the remote keyless entry (RKE) transmitter, the RCDLR module will send a class 2 message to the BCM indicating that an UNLOCK command has been received. The BCM will keep the courtesy lamps ON approximately 10 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 either the ON or RUN position, the courtesy lamps will deactivate in approximately 1 second.

On vehicles without a RCDLR, when the BCM receives a door unlock command from the RKE transmitter, the BCM will keep the courtesy lamps ON approximately 10 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 either the ON or RUN position, the courtesy lamps will deactivate in approximately 1 second.

REAR COMPARTMENT LAMP
The inadvertent power relay also provides battery positive voltage to the rear compartment lamp. When the rear compartment is opened, its switch closes to provide a ground circuit and the rear compartment lamp illuminates. Ground is provided at G401.

INTERIOR LAMPS DIMMING
The second group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination and of incandescent lamps.
- Adjustable pedal position switch
- Door switches and window switches
- Fog lamp switch
- Heated seat switches
- HVAC control head assembly
- Hazard switch
- Outside rearview mirror switch
- Power sunroof switch assembly
- Radio
- Rear compartment lid release switch
- Rear seat audio module
- Steering wheel radio controls
- The instrument panel cluster (IPC)
- Traction control switch

When the ignition switch is turned to the ON position, the VF displays (radio) turn ON at maximum brightness. When the park lamps are ON and the ambient light sensor indicates low light conditions, 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 body control module (BCM) is responsible for the dimming of the interior lights. The BCM receives a varying signal from the I/P dimmer switch. Based on the position of the I/P dimmer switch, the BCM then supplies the appropriate amount of voltage to the interior lamps. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting, with the exception of the I/P backlighting, turns ON at the dimming level indicated by the I/P dimmer switch. 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 position. The I/P backlight is not integrated in the headlamp switch. The automatic lamp control system must determine if it's dark enough to turn the I/P backlights on. Once the I/P backlighting is turned on, the brightness is controlled by the I/P dimmer switch. In rainy weather, etc., the customer may comment that they manually turned on the headlamps, however, the I/P lights did not come on. It is important to note that the I/P backlight will only turn on when indicated by the Automatic Lamp Control's light sensor. This condition is not related to the headlamp switch function, BCM or I/P function. This is considered a normal condition and no parts should be replaced.