The exterior lighting system consists of the following lamps:

The headlamp switch lever is located on the left side of the steering column. A twist-type knob controls the operation of the parking lamps and headlamps. A solid tone will sound as a reminder if you open the drivers door with the key out of the ignition and the park lamps or the headlamps on. When either the parking lamps or headlamps are activated, the following lamps also illuminate:

Low Beam System Operation

The headlamps may be turned on two different ways. First, when the headlamp switch is turned to the ON position, the headlamps will illuminate. Voltage is applied continuously to the headlamp relay low pin 1 through the 60-amp lighting fuse and to headlamps through the 20-amp LH headlamp and 20-amp RH headlamp fuses. The coil is energized when the headlamp switch is switched to the ON position. When the coil is energized the relay provides a ground to low side of the headlamps which then illuminates the low beam headlamps. The second way the headlamps may be turned on is by switching the headlamp switch to the AUTO position. The body control module (BCM) will Illuminate the low beam headlamps when the light sensor detects the appropriate amount of light to turn ON the lamps.

High Beam System Operation

The high-beam headlamp operation is controlled using the turn signal switch lever on the steering column. In order to change headlamp operation from low-beam to high-beam, pull the headlamp dimmer switch until the detent is felt and release.

Flash-to-Pass System Operation

The Flash-to-Pass feature allows the driver to signal the driver of another vehicle his intention to pass. This is achieved by pulling the lever toward the driver, which will cause the high beam operation to illuminate until the lever is released. The operation of the headlamps with the turn signal switch in flash-to-pass mode is the same as the operation of the switch in the high beam mode except the lamps will turn off when the switch is released.

The automatic lamp control (ALC) includes Automatic Lamps ON, Automatic Lamps OFF and Approach Illumination features.

The automatic lamp control function only operates when the Auto Headlamp Control switch is in the AUTO position. The automatic lamp control function includes the following features:

Automatic Lights ON

This feature switches the headlamps and park lamps ON and OFF automatically based on the outside light level. The auto headlamp control switch must be in the AUTO position and the ignition switched ON to enable this feature. The lamps operate as per normal in other switch positions. A light sensor, located in the dashboard between the demist ducts, monitors the amount of light in front of the vehicle. The body control module (BCM) monitors the output of this sensor via BCM connector 2 terminal 2 and determines when the light level is low enough to turn the lamps on. The Automatic Lamps OFF feature works as per normal when Automatic Lamp ON is enabled.

Automatic Lights OFF

This feature switches the headlamps and park lamps OFF automatically. The BCM must sense the following sequence of events before the lamps are switched OFF automatically: A vehicle road-speed of less than 10 km/h (6 mph) without a sudden loss of speed, ignition being switched OFF with the vehicle travelling above 10 km/h (6 mph). The ignition has been switched from ON to OFF and remains OFF. The headlamp switch has not been turned ON after the ignition switch was turned OFF. The driver door has been opened. When the ignition is switched back ON, the lamps turn ON again based on the mode of headlamp operation and the position selected on the automatic headlamp control switch. Turning the switch to OFF deactivates the Automatic Lamps OFF feature. In the event of a system failure, the BCM default status of the lamp control output is ON when the ignition is ON. This gives direct control of the lamps to the automatic headlamp control switch.

Approach Illumination

The approach illumination feature in the BCM turns ON the low beam headlamps and park lamps for 30 seconds when the doors are unlocked with the remote coded key. This provides additional personal security when approaching the vehicle at night. The lights will automatically turn OFF if the vehicle is locked again with the remote coded key within 30 seconds of the approach illumination being activated. When the approach feature is initially activated, subsequent operation of the remote coded key unlock button will reactivate the lights to remain ON for an additional 30 seconds. The approach illumination feature only operates during dark conditions. To enable this to happen, the BCM monitors the output of the light sensor and determines when the light levels are low enough to enable the approach illumination feature to be activated. The headlamps resume normal operation when the ignition is switched ON.

Pontiac GTO vehicles are equipped with the automatic headlamp control feature. With the headlamp switch in the AUTO position, the body control module (BCM) controls the function of the park and low beam of the headlamps. A daytime running lamps (DRL) function is also integrated into the lighting system which automatically illuminates the low beam headlamps at reduced intensity on the first ignition cycle when the vehicle is travelling at speed in excess of 11 km/h (7 mph) and the headlamp switch is in either the OFF or AUTO position. A running lamp dimmer assembly is incorporated into the wiring harness circuit to provide circuit resistance for lamp dimming.

With the ignition switch in START, voltage is applied to the DRL control module through the gage fuse. Operating through the low beams at 86 percent intensity of the normal output, a number of conditions must be met before the daytime running lamps system will work properly:

When the above conditions are met, a path to ground is provided to the coil of the DRL relay by the instrument cluster which sends a ground signal through the dimmer assembly to the ground side of the low-beam headlamps.

The following will prevent DRL operation:

Mechanical System Operation

The front park/turn signal lamps are located next to the headlamp assembly. The turn signal switch lever is located on the left side of the steering column. The park lamp switch is located to the left of the steering column attached to the instrument panel. Twist switch to the first detent position in order to turn on the park lamps. When a turn is signaled, the appropriate front park lamp flashes to signal a turn. The turn signals operate only with the ignition switch in the ON or START positions and will not operate during hazard flasher operation. When making a partial turn, such as when changing lanes, the driver has the option of moving the lever to a detent stop. The turn signal lamps and the turn signal indicator will continue to flash as long as the lever is held in this position and will cancel automatically when the lever is released. The detent position allows a lane change or shallow turn to be made without failing to cancel the turn signal lamp. Moving the lever past the detent position to its furthest upward or downward position will provide conventional turn signal operation.

Circuit Operation

Voltage is applied from the flasher relay when the ignition is in the ON or Accessory position. When the contacts on the turn switch is closed it applies a signal to the flasher relay. Current flows only to the left or right set of lamps from the flasher relay , depending which way the turn signal switch is turned to.

The following lamps are turned on pertaining to the side the switch is activated to:

Mechanical System Operation

The hazard switch is located above the heater control assembly and controls the operation of the hazard lamp circuit. Pressing the hazard switch to the ON position will cause the turn/hazard signal relay to disengage the turn signal circuit and engage the hazard lamp circuit. This causes both turn indicators in the instrument cluster assembly to flash on and off along with all exterior turn signal lamps. The hazard lamp circuit will operate regardless of the position of the ignition switch. Press the hazard switch a second time in order to turn the hazard lamps OFF. Turning the hazard switch OFF disengages the hazard lamp circuit and returns the turn/hazard signal relay to the turn signal mode.

Circuit Operation

Voltage is to the flasher relay. When turned to the on position a signal is supplied to the flasher relay. Current is then provided to the flashers turning them on. The hazard lamps are individually grounded.

The following lamps are turned on when the hazard switch is switched to the ON position:

The tail lamps are located on the vehicle body at each side. Each tail lamp consists of the following single filament bulbs:

Mechanical System Operation

Each of the tail lamps also contains a double filament stop lamp bulb. The stop lamp filament lights under the following conditions:

The high mount stop lamp assembly fitted to the inside of the vehicle and to the rear spoiler uses a strip of light emitting diodes (LEDs) for illumination. The stop lamp is designed to operate in conjunction with the tail lamps whenever the brake pedal is depressed.

Circuit Operation

Voltage is applied continuously from the STOP LAMPS fuse to the stop lamp switch. When the brake pedal is depressed voltage flows to the center high mounted stop lamp (CHMSL) and left and right stop lamps.

S307 applies voltage to the following lamps:

The backup lamps are designed to operate with the ignition in the ON position. Placing the transaxle in the R position closes the backup lamp circuit and turns the backup lamps ON.

Manual Transaxle

On vehicles equipped with a manual transaxle, the circuit closes through the backup lamp switch. When the ignition switch is in the RUN or START positions voltage is applied to the TURN SIGNALS fuse, located in the instrument panel fuse block. Current flows through S206 then through cavity 7 of C206 finally going to the backup lamp switch cavity A. When the switch is closed it allows voltage to be applied to the backup lamp supply voltage circuit. Current is split through S905 to the backup lamps which turns ON the backup lamps.

Automatic Transaxle

On vehicles equipped with an automatic transaxle, the circuit closes through the park neutral position (PNP) switch. When the ignition switch is in the RUN or START positions it applies power to the TURN SIGNALS fuse, located in the instrument panel fuse block. Current then flows through S206 then finally going to the PNP switch cavity 11. When the switch is closed it allows voltage to be applied to the backup lamp supply voltage circuit. Current is split through S905 to the backup lamps which turns ON the backup lamps.

There are two rear license plate lamps located on the rear decklid directly over the license plate. Each rear license plate lamp contains one clear, single filament bulb. The rear license plate bulbs will light when either the parking lamps or headlamps are activated.