Interior Lighting Systems

Interior Lighting Systems Description and Operation

Interior Lamps

The interior lighting consist of two groups. This first group includes lamps that may not be dimmed.

* Dome lamp
* I/P compartment lamp
* Reading lamps
* Rear compartment courtesy lamp
* Vanity mirror lamps

Dome Lamps

The dome lamp switch has 3 positions: DOOR, OFF, and ON. The dome lamp OFF signal circuit and the dome lamp ON signal circuit to the body control module (BCM) are both supplied with battery positive voltage at all times. The BCM monitors both signal circuits for voltage drop and when a high voltage is detected at both signal circuits, which is the case when the dome lamp switch is in the DOOR position, dome lamp operation will be controlled by the BCM. When any door is opened, the associated door jamb switch closes providing a door open input to the BCM. The BCM responds by applying battery positive voltage to the dome lamp control circuit illuminating the dome lamp. The dome lamp will turn OFF immediately if the ignition switch is turned to the ON position or approximately 20 seconds after all doors are closed. The dome lamp will normally turn OFF using the theater dimming feature when controlled by the BCM.

When the dome lamp switch is placed in the ON position, the dome lamp ON signal circuit is switched to ground providing an input to the BCM. The BCM responds to the voltage drop on the dome lamp ON signal circuit by supplying battery positive voltage to the dome lamp for continuous operation or until the dome lamp switch is placed in the OFF or DOOR positions. If the operator inadvertently leaves any interior lamp ON, the BCM will turn all interior lamps OFF after 10 minutes has passed since any switch activation has been detected by the BCM.

With the dome lamp switch in the OFF position, the dome lamp OFF signal circuit is switch to ground providing an input to the BCM. The BCM responds to the voltage drop on the dome lamp signal OFF circuit by disabling the dome lamp control circuit keeping the dome lamp from illuminating when any of the doors are opened.

Instrument Panel (I/P) Compartment Lamp

The inadvertent power supply voltage circuit from the BCM provides battery positive voltage to the I/P compartment (glove box) lamp. When the I/P compartment is opened, the I/P compartment lamp switch contacts close providing a path to ground and the I/P compartment lamp illuminates. If the operator inadvertently leaves the I/P compartment door open with the I/P compartment lamp ON, the BCM will turn all interior lamps OFF after 10 minutes has passed since any switch activation has been detected by the BCM.

Keyless Entry Interior Illumination

When the operator uses the keyless entry transmitter in order to unlock the doors, the BCM receives a door-unlock signal. The BCM must receive inputs from various systems that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF, and all doors are closed before the BCM will activate the interior lamps. The courtesy lamps will remain ON for 20 seconds after the door is closed. The BCM will turn off the courtesy lamps 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 RUN or CRANK position, the courtesy lamps will turn OFF immediately.

Rear Compartment Courtesy Lamp

The BCM provides battery positive voltage to the rear compartment courtesy lamp. When the rear compartment is opened, the rear compartment latch opens providing a rear compartment open input to the BCM. The BCM responds by applying battery positive voltage to the rear compartment lamp control circuit illuminating the rear compartment lamp.

Reading Lamps

The inadvertent power supply voltage circuit from the BCM provides battery positive voltage to each reading lamp. When the reading lamp switch is activated, the switch contacts close providing a path to ground and the reading lamp illuminates. If the operator inadvertently leaves a reading lamp ON, the BCM will turn all interior lamps OFF after 10 minutes has passed since any switch activation has been detected by the BCM.

Vanity Mirror Lamps

The inadvertent power supply voltage circuit from the BCM provides battery positive voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, a switch closes providing ground and the vanity lamp illuminates. If the operator inadvertently leaves a vanity mirror open with the lamp ON, the BCM will turn all interior lamps OFF after 10 minutes has passed since any switch activation has been detected by the BCM.

Battery Rundown Protection/Inadvertent Power

The BCM inadvertent power supply voltage circuit provides battery positive voltage to all of the interior map lamps, I/P compartment lamp, and vanity mirror lamps. In the event that any of these lamps were to remain illuminated for a period of more than 10 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power supply voltage circuit to prevent total battery discharge.

Interior Lamps Dimming

The second group includes lamps which may be dimmed.

* Door lock switch driver
* Outside rearview mirror switch
* Power sun roof switch
* Power sun roof tilt switch
* Power window switches
* Headlamp switch
* Hazard switch
* HVAC control head assembly
* Instrument panel cluster
* Radio
* Steering wheel control switch - left
* Steering wheel control switch - right
* Traction control switch
* Transmission shift lever position indicator

When the headlamp switch is placed in the PARK or HEAD position, the park lamp switch signal circuit provides an input to the body control module (BCM). The BCM responds by applying voltage to the park lamps as well as the dimming control circuits illuminating all components with interior backlighting. All LED backlighting turns ON at the dimming level indicated by the instrument panel (I/P) dimmer switch. The I/P dimmer switch is a momentary type switch and utilizes a resistor ladder to accomplish dimming controls. The I/P dimmer switch contains a battery positive voltage reference circuit and a signal circuit from the BCM. When the I/P dimmer switch is held in the decrease brightness position, the BCM receives a low voltage signal via the I/P dimmer switch signal circuit. The BCM responds by decreasing the brightness of all interior backlighting by decreasing the voltage supplied to the backlighting components via the dimming control circuits. When the I/P dimmer switch is held in the increase brightness position, the BCM receives a high voltage signal via the I/P dimmer switch signal circuit. The BCM responds by increasing the brightness of all interior backlighting by increasing the voltage supplied to the backlighting components via the dimming control circuits.