The exterior lighting system consist of the following lamps:

The headlamps may be turned ON 2 different ways. First, when the driver places the headlamp switch in the HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the AUTO position, for automatic lamp control (ALC). During ALC, the headlamps will be OFF in daylight conditions, or low beam operation in low light conditions. Battery positive voltage is supplied to the low beam relay and the high beam relay in the underhood fuse block. When low beam headlamps are requested, the body control module (BCM) supplies ground to the coil side of the low beam relay. This activates the relay and the relay supplies voltage to the left hand low beam headlamp through the LH LOW BEAM fuse and to the right hand low beam headlamp through the RH LOW BEAM fuse. Ground for the left hand low beam headlamp is provided at G101. Ground for the right hand low beam headlamp is provided at G102. When high beam headlamps are requested, the BCM supplies ground to the coil side of the high beam relay. This activates the relay and the relay supplies voltage to the left hand high beam headlamp through the LH HIGH BEAM fuse and to the right hand high beam headlamp through the RH HIGH BEAM fuse. Ground for the left hand high beam headlamp is provided at G101. Ground for the right hand high beam headlamp is provided at G102.

The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.2 and 4.9 volts depending on outside lighting conditions. The body control module (BCM) provides a low reference ground and 5-volt reference signal to the ambient light sensor. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. In daylight conditions the BCM will apply ground to the DRL relay control circuit causing the DRL relay coil to energize. With the DRL relay energized, the switch contacts close allowing battery voltage to flow through the DRL fuse via the DRL control circuit illuminating the low beam headlamps at reduced intensity. The DRL control circuit that supplies the low beam headlamp fuses with voltage contains a loop of wire that acts as resistance. This resistance is responsible for the low beam headlamps illuminating at a reduced intensity. Any function or condition that turns on the headlamps will cancel DRL operation.

With the ignition switch in the ON position, and the park lamps or low beam headlights ON, the fog lights will illuminate when the driver presses the fog lamp switch. The FRT FOG fuse in the underhood fuse block supplies battery positive voltage to the switch side of the FRT FOG relay. When the fog lamp switch is pressed, the body control module (BCM) fog lamp switch input is grounded. Ground is provided at G203. The BCM will then energize the FRT FOG relay control circuit. The current flow is now from the FRT FOG relay to both front fog lamps and to ground. Ground is provided at G101 and G102. The state of the fog lamps , either ON or OFF, will remain the same until the fog lamp switch is pressed again, or the ignition switch is cycled OFF and ON. Fog lamp operation will be cancelled whenever the park lamps, are turned OFF or the high beam headlights have been selected.

The park, tail, and marker lamps, including the license lamps, are turned ON when the headlamp switch is placed in the PARK or HEADLAMP position, or anytime the headlights are requested. The PARK LAMPS fuse in the I/P fuse block supplies battery positive voltage to the PARK LAMP relay switch contacts. The PARK LAMPS fuse in the I/P fuse block also supplies battery positive voltage to the PARK LAMP relay coil. When the park lamps are turned ON, the body control module (BCM) energizes the park lamp relay. Current flow is from the PARK LAMP relay to their respective park and marker lamps and to ground. Ground is provided at G101, G102, G401, and G403.

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 body control module (BCM) indicating that an UNLOCK command has been received. The BCM will then flash the park lamps twice. With all the doors closed, and the RKE transmitter is used to lock the doors, the park lamps will flash twice. The park lamps will not flash if the rear compartment is opened using the RKE transmitter.

On vehicles without a RCDLR, when the BCM receives a door unlock command from the RKE transmitter, the BCM will then flash the park lamps twice. With all the doors closed, and the RKE transmitter is used to lock the doors, the park lamps will flash twice. The park lamps will not flash if the rear compartment is opened using the RKE transmitter.

The body control module (BCM) is responsible for controlling the turn signals and hazard lamps. When the turn signal switch is placed in either the left turn or right turn position, the BCM receives a signal from the turn signal switch. The BCM then sends an on-off voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator. When the hazard switch is pressed, the BCM receives a signal from the hazard switch. The BCM then will send an on-off voltage signal to all the turn signal lamps. All the turn signal lamps will flash including both IPC turn signal indicators.

The body control module (BCM) is responsible for controlling the stop lamps. When the driver presses the brake pedal, the BCM will receive a signal from the brake pedal position sensor. The BCM then supplies battery positive voltage to both left and right stop lamp assemblies and to the center high mounted stop lamp (CHMSL). The stop lamps are grounded at G401 and G403. The CHMSL is grounded at G302.

The R-BEC 1 fuse in the underhood fuse block supplies battery positive voltage to the BACKUP LAMP relay through the BACKUP LAMP fuse. When the gear selector is placed in reverse, the body control module (BCM) supplies ground to the BACKUP LAMP relay. This energizes the BACKUP LAMP relay and current flows from the BACKUP LAMP relay to the backup lamps and then to ground. The backup lamps are grounded at G401 and G403.

The body control module (BCM) used in this vehicle controls the lighting system through circuits that enable both the exterior lamp functions of park, head, and fog lamps as well as 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.