Interior Lamps

GENERAL DESCRIPTION

Courtesy Lights
The Courtesy Lights come on when either the driver's or passenger's door is opened with the ignition off (if there is low ambient light) and when selected by the Courtesy Light Switch. The Courtesy Lights also will stay on for a timed delay when entering the vehicle through the driver's door.

The Courtesy Light system consists of the following lamps: LH and RH Door Courtesy Lamps, LH and RH Door Warning Lamps, LH and RH Footwell Courtesy Lamps, Stowage Lamp and the Reading/Courtesy Lamps in the Rear View Mirror. The Body Computer Module (BCM) controls the Courtesy Lights by turning the Courtesy Light Relay on and off based on inputs from the Courtesy Light Switch, Door Ajar Switches, Ignition Switch and the Twilight Photocell.

The Courtesy Light system features the following:

Illuminated Entry
Illuminated Entry keeps the Courtesy Lights on for 30 seconds after the driver's door is closed if the ignition is off when entering the vehicle. The BCM controls the time delay. If the ignition is turned on before 30 seconds has elapsed the Courtesy Lights will turn off. The 30 second delay is not activated on the first driver's door closure after the ignition is turned off. This prevents the 30 second delay from operating when exiting the vehicle and prepares the 30 second delay for entering the vehicle only.

Battery Guard
Battery Guard prevents excessive battery current drain. This feature prevents the Courtesy Lights from being turned on in high ambient light conditions when the doors are opened. It also turns off the Courtesy Lights after to minutes if they have been left on accidentally when the ignition is off. Battery Guard will operate regardless of the Courtesy Light Switch and door status.

CIRCUIT OPERATION

Courtesy Lights Control
The BCM controls the Courtesy Lights based on ambient light conditions, Door Ajar Switch status, Courtesy Light Switch status and Ignition Switch status.

The BCM monitors ambient light conditions through the Twilight Photocell at terminal 1D3. The Twilight Photocell is a variable resistor whose resistance changes as the level of ambient light changes around it. As ambient light decreases the resistance of the Twilight Photocell increases. The voltage level at the BCM twilight photocell input increases as the Twilight Photocell resistance increases. The Twilight Photocell can be checked by entering diagnostics and selecting BD44. The value should be close to 100% in darkness and close to 0% in bright daylight. If the Twilight Photocell circuit opens or shorts to ground code B119 will set.

Door position is monitored through the Door Ajar Switches by the BCM. When a door is opened the respective Door Ajar Switch closes and grounds the door ajar switch input to the BCM. When a door is closed the Door Ajar Switch opens and removes ground from the BCM input. The BCM monitors the LH door at terminal 2A2 and the RH door at terminal 2A3. The Door Ajar Switches can be tested by entering diagnostics and selecting BCM Inputs B103 or B104. The input should be LO when the door is open and HI when the door is closed.

Whenever a door is opened the BCM turns on the Courtesy Lights if there is low ambient light (see Battery Guard in General Description) and the ignition is off. When entering the vehicle through the driver's door the BCM keeps the Courtesy Light Relay energized for 30 seconds after the driver's door is closed (LH Door Ajar Switch opens). If the Ignition Switch is turned to RUN before the 30 second delay has elapsed the BCM will turn the Courtesy Lights off.

The Courtesy Lights can be turned on by the Courtesy Light Switch regardless of door position when the ignition is off or on. When the Courtesy Light Switch is pressed the Headlight Switch sends a courtesy light request to the BCM (through CKT 928 the lighting data line) and turns on the Courtesy Lights LED. The BCM then turns on the Courtesy Lights. If the Courtesy Light Switch is pressed again the Headlight Switch requests the Courtesy Lights off through the lighting data line and turns off the LED. The BCM turns off the Courtesy Lights. The Courtesy Light Switch can be tested by entering diagnostics and selecting Lighting Input LI01. The input should be HI when the switch is pressed and held and LO when the switch is not pressed.

The BCM monitors the Ignition Switch position at terminal 3D6 (the IGN 3 input).

Courtesy Lights Power
Battery voltage is applied to the Courtesy Lights at all times through Fuse D1, Fuse D3 and CKTs 240 and 640 (see schematic). All of the Courtesy Lights are grounded through CKT 149, the Courtesy Light Relay (when energized) and CKT 1504 at ground G309.

The BCM energizes the Courtesy Light Relay by grounding CKT 690 at terminal 3C7 (the courtesy light relay output). When energized the Courtesy Light Relay completes the ground circuit by connecting CKTs 149 and 1504.

The Courtesy Light circuit can be tested by entering diagnostics and selecting BCM Output BO18. When the output is LO the Courtesy Light Relay should energize and the Courtesy Lights should turn on. The relay and Courtesy Lights should turn off when the output is HI.