For 1990-2009 cars

### Interior Lamps

The interior lamps consist of 2 groups. The first group are those lamps which may not be dimmed. The 2nd group includes lamps that may be dimmed.

• | Inside rearview mirror lamps

• | Rear Compartment lamp

### Courtesy Lamps

The INTERIOR LIGHTS fuse supplies battery voltage to the inadvertent load control relay located in the body control module (BCM). The BCM applies ground to the inadvertent relay control circuit which energizes the inadvertent load control relay coil. With the relay coil energized, the switch contacts close allowing battery voltage to flow from the INTERIOR LIGHTS fuse to the inside rearview mirror lamps through the courtesy lamp supply voltage circuit. The inside rearview mirror lamps are controlled by a 3 position (OFF, DOOR, ON) switch. When the inside rearview mirror switch is placed in the DOOR position, the lamps are controlled by the BCM by grounding the courtesy lamp control circuit. When any door is opened, the jam switch contacts close and the BCM receives a door-open input. If the BCM receives a door lock or unlock input, the BCM will activate the inadvertent relay control circuit, providing battery voltage to the inside rearview mirror lamps. The BCM also provides ground to the inside rearview mirror lamps through the courtesy lamp control circuit.

The courtesy lamps will remain illuminated approximately 10 seconds after the last door closes. Courtesy lamps also turn ON prior to any door being opened, and remain illuminated approximately 30 seconds after the driver removes the ignition key.

The courtesy lamps will normally turn OFF using the theater dimming feature. The BCM provides a pulse width modulated ground to the courtesy lamps for the theater dimming feature. The BCM turns OFF the courtesy lamps if a door lock command is received after all of the doors are closed, or if the ignition switch is turned to either the ON or RUN position.

The BCM will provide interior lamp illumination in the event that an air bag has been deployed. Upon deployment of the air bag the inflatable restraint sensing and diagnostic module (SDM) will send a GMLAN serial data message to the BCM. The BCM will activate the interior lamps approximately 15 seconds after air bag deployment if the Photocell Status is DARK and the ignition is in the ON position. The interior lamps will remain illuminated until there is a change in the power mode.

### Keyless Entry Interior Illumination

When the driver uses the remote function actuator (RFA) transmitter to unlock the doors or press the panic button, the BCM will keep the courtesy lamps ON for 30 seconds. If the door locks are activated to the UNLOCK or LOCK position, or if the ignition switch is turned to either the RUN or CRANK position, the courtesy lamps turn OFF immediately. The BCM keeps the courtesy lamps on for 40 seconds after an alarm event is completed.

### Rear Compartment Lamp

The INTERIOR LIGHTS fuse supplies battery voltage to the body control module (BCM). The BCM applies battery voltage to the rear compartment lamp through the rear compartment lamp control circuit. The rear compartment lamp is provided ground permanently at G402. When the BCM receives a rear hatch open input, the BCM will activate the rear compartment lamp control circuit to provide battery voltage to the rear compartment lamp.

### Interior Lamps Dimming

Interior lamps dimming are lamps that may be dimmed by operating the instrument panel (I/P) dimmer switch. This group consist of the following lamps:

• | Fog lamp switch

• | Hazard switch

• | HVAC control head assembly

• | Instrument panel cluster (IPC)

• | Outside rearview mirror switch

• | PRNDL

• | Radio

• | Steering wheel controls

• | Traction Control Switch

• | Window switches

When the park lamps are ON and the ambient light sensor indicates low light conditions, all back lighting will turn ON at the dimming level indicated by the I/P dimmer switch. When the turn signal/multifunction switch is placed in the PARK or HEADLAMP positions, the body control module (BCM) energizes the park lamp relay coil control circuit and dims the interior lamps to the dimming level indicated by the I/P dimmer switch. When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all back lighting lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX , all back lighting components respond from minimum intensity to maximum brightness in response to the I/P dimmer switch.

The driver may select parade mode by manually turning on the park lamps during daylight conditions.

### Battery Rundown Protection/Inadvertent Power

To provide battery run down protection, the interior lamps will be deactivated automatically under certain conditions. The body control module (BCM) initiates a 20 minute timer if the interior lamp relay control output is still active, and the ignition switch is in the OFF position. At the end of the designated time, the BCM will deactivate the interior lamp relay, disabling the interior lamps. This feature will be cancelled if any power mode other than OFF becomes active. The BCM will reset the timer if any interior lamp switch is turned ON, a door is opened, or the remote control door lock receiver (RCDLR) module is activated.