The exterior lighting system consist of the following lamps:

The headlamps may be turned on in two 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 control the headlamps will be in day time running lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions.

The automatic lamp control (ALC) system and the DRL feature can be temporarily disabled by performing the following procedure:

Note: The ALC and DRL cannot be turned off on the Canadian vehicles.

1. Turn the ignition to RUN.
2. Press the DOME OVERRIDE button four times within six seconds.

A chime will sound informing you that the system is off. The system will remain disabled until the ignition is cycled off and then on or by pressing the DOME OVERRIDE button four more times within six seconds. The chime will sound again signaling that the system has been reactivated.

The engine wiring harness junction block supplies battery positive voltage to the normally open headlamp relay switch circuit. The TBC 10 A fuse in the engine wiring harness junction block supplies battery positive voltage to the headlight and dimmer switch assembly. The body control module (BCM) also supplies battery positive voltage to the headlamp relay coil circuit for automatic headlight control. The coil circuit of the headlamp relay is then grounded at G102. When the driver places the headlamp switch in the HEADLAMP position, the headlamp relay is energized. Depending on the position of the dimmer switch, the current flow is to both the left and right headlamp fuse, and to either the low or high beam headlamps. From the dimmer switch, the current flow is to ground at G203. The TCB 10 A fuse in the engine wiring harness junction block supplies battery positive voltage to the headlight and dimmer switch assembly flash to pass switch. When the headlamp dimmer switch handle is pulled toward the driver, both flash-to-pass switches close, one grounding the high beam circuit at G203. A second flash to pass switch also closes providing battery positive voltage to the BCM flash-to-pass input. With the headlights in the low beam position, the high beams may be momentarily turned on or flashed with the dimmer switch handle.

If the headlight switch is left in the ON position, the inadvertent power control feature will turn off the headlights approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain on until turned off or the battery runs dead.

The high beam indicator is illuminated when the instrument cluster receives a class 2 serial data message from the BCM that the high beams are illuminated.

The ambient light sensor is a light sensitive transistor that varies its voltage signal to the body control module (BCM) in response to changes to the outside (ambient) light level. When the BCM receives this signal it will either turn on the daytime running lamps (DRL) or the headlight relay for auto headlamp operation. Any function or condition that turns on the headlights will cancel the daytime running lamps operation. The daytime running lamps (DRL) separate lamps independent of the headlamps. With the headlight switch in the OFF position, the DRL will either be turned ON or OFF, after an approximate 8 second delay depending on whether daylight or low light conditions are sensed. The DRL 10 A fuse in the engine wiring harness junction block supplies battery positive voltage to the daytime running lamp (DRL) relay switch contacts. The IGNE 10A fuse in the engine wiring harness junction block supplies ignition positive voltage to the DRL relay coil. When the BCM energizes the DRL relay in daylight conditions, the current flow is to both DRL lamps and to ground G100. The DRL will operate when the ignition switch is in the RUN position, the gear selector is not in the PARK position and the parking brake is released. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate.

The automatic lamp control (ALC) system and the DRL feature can be temporarily disabled by performing the following procedure:

Note: The ALC and DRL cannot be turned off on the Canadian vehicles.

1. Turn the ignition to RUN.
2. Press the DOME OVERRIDE button four times within six seconds.

A chime will sound informing you that the system is off. The system will remain disabled until the ignition is cycled off and then on or by pressing the DOME OVERRIDE button four more times within six seconds. The chime will sound again signaling that the system has been reactivated.

With both the ignition switch in the [RUN] position, and the park lamps ON, the fog lights will illuminate when the driver places the fog lamp switch in the ON position. The FOG LPS 15 A fuse in the engine wiring harness junction block supplies battery positive voltage to the fog lamp relay switch circuit. The park lamp relay supplies battery positive voltage to the fog lamp relay coil. With the headlamp switch in either the park or headlamp position, and the fog lamp switch is paced in the ON position, the body control module (BCM) will energize the fog lamp relay control circuit. The BCM receives the park lamp ON signal from the interior park lamps supply voltage signal circuit. The current flow is from the fog lamp relay to both front fog lamps and to ground G100. The state of the fog lamps will remain the same until the fog lamp switch position is changed, 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 rear fog lamps are controlled in much the same way, however the front fog lamps must be on in order to turn on the rear fog lamps. The rear fog lamps have there own relay, and both the relay control and current flow are the same as the front fog lamps.

The park, tail and marker lamps, including the license lamps, are turned on when the headlamp switch is placed in the PARK or ON position or anytime the headlights are requested. The PARK LPS 30 A fuse in the engine wiring harness junction block supplies battery positive voltage to both the park lamp relay switch contacts and the park lamp coil circuit. The body control module (BCM) provides a ground or control circuit to the park lamp relay coil circuit. When the park lamps are turned on the BCM energizes the park lamp relay. Current flow is from the park lamp relay to the FR PRK 10 A fuse, RR PRK 10 A fuse, LR PRK 10 A fuse, and the TRL PRK 15 A fuse, and to their respective park and marker lamps. The front park and marker lamps are grounded at G100. The rear park and marker lamps are grounded at G401. The license lamps are grounded at G401. If the headlight switch is left in the ON position, the inadvertent power control feature will turn off the park, tail and marker lamps approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the park, tail and marker lamps will remain on until turned off or the battery runs dead.

The CTSY LMP 15 A fuse in the engine wiring harness junction block supplies battery positive voltage to both the inadvertent power relay switch contacts and the inadvertent power relay coil circuit. The body control module (BCM) provides a ground or control circuit to the park lamp relay coil circuit. When the driver presses the cargo lamp switch, the BCM energizes the inadvertent power relay. Current flow is from the inadvertent power relay to the cargo lamps. The cargo lamps are grounded at G203.

The SEO 1 15 A fuse in the engine wiring harness junction block supplies battery positive voltage to both the exterior courtesy lamp relay switch contacts and the exterior courtesy lamp relay coil circuit. When the driver or passenger door is opened the body control module (BCM) energizes the exterior courtesy lamp relay. Current flow is from the exterior courtesy lamp relay to both outside rear view mirror exterior courtesy lamps. The exterior courtesy lamps are grounded at G200 and G203. When the remote function actuation (RFA) module receives a door unlock command from the remote function actuator transmitter, the RFA module will send a message to the body control module (BCM) indicating that an UNLOCK command has been received. The BCM must have inputs that indicate that the ignition switch is OFF, all the doors are closed. The BCM will activate the exterior courtesy lamp relay illuminating the power outside mirror exterior courtesy lamps. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the ON or RUN position the exterior courtesy lamps will deactivate immediately.

When an outside door handle is lifted or a door is opened, the exterior courtesy lamps illuminate.

The HAZ LP 20 A fuse in the engine wiring harness junction block supplies battery positive voltage to the hazard switch assembly. The TURN 20 A fuse in the engine wiring harness junction block supplies Ignition positive voltage to the turn signal switch assembly. With the ignition switch in the RUN or START position, ignition positive voltage is connected through the turn signal and hazard switch assembly to the flasher module which is grounded at G203. When the turn signal switch is placed in either the left or right position, the circuit is complete from the flasher module through the turn signal switch to the turn signal lamps and to ground. The flasher module then sends an on-off voltage signal through the turn signal switch to either the left or right turn signals and their instrument panel cluster (IPC) indicator. The audio chime is also activated when the turn signals are on. When the hazard switch is pressed, all turn signal lamps will flash including both IPC turn indicators. The front turn signals are grounded at G100. The rear turn signals are grounded at G401.

For trailer wiring, separate turn signal circuits are connected through the turn signal switch for the trailer wiring harness. The TRL L TRN 10 A fuse and TRL R TRN 10 A fuse in the engine wiring harness junction block supplies the signal for the trailer turn signal lamps.

The STOP LPS 20 A fuse in the engine wiring harness junction block supplies battery positive voltage to the normally open stop lamp switch. When the driver presses the brake pedal, the switch contacts close and battery positive voltage is supplied to both the VEH STOP 10 A fuse and the CHMSL 10 A fuse. Battery positive voltage is also supplied by the STOP LPS 20 A fuse in the engine wiring harness junction block to the turn signal switch. The current flow is now to the stop lamps which are grounded at G401. The center high mounted stop lamp (CHMSL) is grounded at G410 or G203 for pick ups.

For trailer wiring, a separate stop lamp circuit is connected through the engine wiring harness junction block from the CHMSL 20 A fuse to the trailer wiring harness.

The B/U LP 25 A fuse in the engine wiring harness junction block supplies battery positive voltage to the normally open backup lamp switch. When driver places the gear selector lever is in the REVERSE position, the backup lamp switch closes and the current flow is from the backup lamp switch through the VEH B/U 15 A fuse to the backup lamps. The backup lamps are grounded at G401.

For trailer wiring, a separate backup lamp circuit is connected through the engine wiring harness junction block from the TRLR B/U 10A fuse to the trailer wiring harness.

The clearance lamps are turned on when the headlamp switch is placed in the PARK or ON position or anytime the headlights are requested. The PARK LPS 30 A fuse in the engine wiring harness junction block supplies battery positive voltage to both the park lamp relay switch contacts and the park lamp coil circuit. The body control module (BCM) provides a ground or control circuit to the park lamp relay coil circuit. When the park lamps are turned on the BCM energizes the park lamp relay. Current flow is from the park lamp relay to the INT PRK 10 A fuse, and to clearance lamps. The clearance lamps are grounded at G200.

The inadvertent power relay provides battery positive voltage to the cargo lamp and the underhood lamp. When the respective normally open switch is closed, the switch provides a ground circuit and the lamp illuminates. The cargo lamp is grounded at G203. The underhood lamp is grounded at G102.

The IGN 1 10 A fuse in the engine wiring harness junction block supplies battery positive voltage to the to both the headlamp leveling switch and the headlamp leveling motors through different terminals in the junction block. The headlamp leveling switch varies the amount of current to the actuators causing them to move simultaneously up or down to each selected position. Ground for the actuators and the switch are supplied by G100.