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 daytime running lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions.

Low Beams

Battery positive voltage to the headlamp switch is supplied by the HDLP SW fuse in the IP fuse block. When the headlamp switch is in the HDLP position, the headlamp power relay coil is energized. A voltage signal is also sent to the body control module (BCM) signaling that the headlamp switch is activated. The headlamp power relay coil is grounded at G102. When the headlamp power relay is energized, the relay supplies battery voltage to the LT HDLP and RT HDLP fuses. Both low beam headlamps are grounded by the multifunction headlamp dimmer switch in the low beam position through the normally closed headlamp grounding relay in the body relay block to G200.

High Beams

Battery positive voltage to the headlamp switch is supplied by the HDLP SW fuse in the IP fuse block. When the headlamp switch is in the HDLP position, the headlamp power relay coil is energized. A voltage signal is also sent to the body control module (BCM) signaling that the headlamp switch is activated. When the headlamp switch is in the AUTO or PARK position and the ambient light sensor detects darkness, the BCM produces a voltage signal that will also energize the headlamp power relay. The headlamp power relay coil is grounded at G102. When the headlamp power relay is energized, the relay supplies battery voltage to the LT HDLP and RT HDLP fuses. The RH high beam headlamp receives current directly from the RT HDLP fuse. When the headlamp switch is in the HDLP position, the BCM removes the ground path to the headlamp grounding and DRL relay coils. This allows current to flow to the LH high beam headlamp through the normally closed contacts of the DRL relay. Both high beam headlamps are grounded by the multifunction headlamp dimmer switch in the high beam position through the normally closed contacts in the headlamp grounding relay to G200. A ground signal is also sent to the BCM in order to confirm high beam operation.

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 headlights for auto headlamp operation. Any function or condition that turns on the headlights will cancel the daytime running lamps operation. With the headlight switch in the OFF position, the headlights 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 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 DRL relay is supplied battery positive voltage by the FOG LP fuse in the underhood fuse block. When the BCM requests DRL operation, the DRL relay coil and headlamp grounding relay coil are grounded by the BCM activating both relays. The energized headlamp grounding relay removes the ground utilized in normal headlamp operation to the multifunction headlamp dimmer switch . The energized DRL relay reroutes the LH high beam supply voltage circuit to ground at G102. These actions result in the LH and RH high beam headlamps to function in a series circuit at a reduced intensity.

DRL operation in Manual Transmission equipped vehicles will occur when the ignition switch is in the RUN position, and the parking brake is released.

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

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 park, tail, marker and 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 LP fuse in the engine wiring harness junction block supplies battery positive voltage to the park lamp relay coil and the headlamp switch. The body control module (BCM) provides a ground, or control circuit, to the park lamp relay coil circuit during ALC operation. When the park lamps are turned on during ALC, the BCM energizes the park lamp relay. The park lamps can also be supplied battery positive voltage directly from the headlamp switch. Current flow is to the FR PARK fuse, LR PARK fuse, RR PARK fuse and the TRL PARK fuse, and to their respective park, marker and license lamps. The front park and marker lamps are grounded at G111 and G112. The rear park, tail, marker and license lamps are grounded at G475 and G422. If the headlight switch is left in the ON position, the park, tail and marker lamps will remain on until turned off or the battery runs dead.

The HAZ LP fuse in the underhood fuse block supplies battery positive voltage to the multifunction hazard switch assembly. The TURN fuse in the IP fuse block supplies Ignition positive voltage to the multifunction turn signal switch assembly. With the ignition switch in the RUN or START position, ignition positive voltage is connected through the multifunction turn signal and hazard switch assembly to the flasher module which is grounded at G205. When the turn signal switch is placed in either the left or right position, the circuit is complete from the flasher module to the turn signal lamps and to ground. The flasher module 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 activated, all turn signal lamps will flash including both IPC turn indicators. The front turn signals are grounded at G111 and G112. The rear turn signals are grounded at G475 and G422.

The STOP LP 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 VECHMSL fuse and the TRCHMSL fuse. Battery positive voltage is also supplied to the multifunction turn signal switch. The current flow is now to the stop lamps which are grounded at G475 and G422. The center high mounted stop lamp (CHMSL) is grounded at G202.

The B/U 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 fuse to the backup lamps. The backup lamps are grounded at G475 and G422.