The exterior lighting system consists of the following features:

The headlamps consist of 2 interchangeable single filament bulbs or 2 high intensity discharge (HID) arc tubes and ballast on each side of the vehicle which provide high and low beams. The lower bulb in the headlamp is the high beam and the upper bulb is the low beam.

The headlamps may be turned ON in 3 different ways:

With the headlamp switch in the ON position, the headlamp switch headlamp ON signal circuit is grounded through the turn signal/multifunction switch at G200. In response to this input, the instrument panel module (IPM) provides ground to either the headlamp low beam relay control circuit or the headlamp high beam relay control circuit. The position of the headlamp dimmer switch determines which relay coil has ground. The IPM supplies ground to the relay coil circuits, if the headlamps are necessary. The underhood fuse block supplies battery positive voltage to both relay switch circuits. When the low beam relay coil is energized, current flows through the LT LOW BEAM and the RT LOW BEAM fuses to the low beam headlamps. The low beam headlamps are grounded at G104. When the headlamp high beam relay coil is energized, current flows through the LT HI BEAM and the RT HI BEAM fuses to the high beam headlamps. The high beam headlamps are also grounded at G104. When the headlamp dimmer switch lever is pulled toward the driver, the flash to pass (FTP) switch closes. This grounds the IPM flash to pass switch signal. In response to this input, the IPM energizes the high beam relay. Both high beams will remain ON until the driver releases the headlamp dimmer switch handle. If the low beam headlamps were ON during FTP operation, the low beams remain ON. The headlights may be switched to high beam with the opposite movement of the headlamp dimmer switch lever. With the headlamp dimmer switch in the high beam position the IPM sends a message via GMLAN to the instrument panel cluster (IPC) requesting the IPC to illuminate the high beam indicator. If the headlamp switch is left in the ON position, the inadvertent power control feature will turn OFF the headlights 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.

During automatic lamp control (ALC), the headlamps will be in low beam operation during low light conditions. A HEADLAMPS SUGGESTED message will appear on the driver information center (DIC) when the headlamps and park lamps are OFF due to all exterior lighting controls being inactive when dark conditions are sensed. The auto position of the headlamp switch is supplied ground at G200 and enables the auto lamp feature. When the ignition is ON, the IPM will automatically turn the headlamps ON or OFF according to the Light/Dark photocell Status.

The headlamps ON with wipers feature operates when the following conditions are true:

When the headlamps ON with wipers feature is active the DIC will display the HEADLAMPS SUGGESTED message.

The high intensity discharge (HID) system is made up of the ballast and arc tube. The headlamp ballast receives the headlamp low beam supply voltage, which would normally be used to directly supply the low beam headlamp. Each ballast has a separate ground. The HID headlamp operation consist of 3 states. The startup or strike state, run up state, and steady state. When the headlamp switch is placed in the ON position, the ballast may draw up to 20 amps. This is referred to as the strike state. The ballast will provide multiple high voltage pulses to the arc tube in order to start the bulb. The voltage provided by the ballast during the startup state ranges from -600 to +600 volts. Once an arc is established, the ballast will provide a higher then steady state voltage to the arc tube in order to keep the bulb illuminated. This is called the run up state. On a cold bulb this state could last as long as 41 seconds. On a hot bulb, the run up state may last as long as 15 seconds. Steady state operation begins when the bulb reaches the 35 watt power level. The ballast provides the bulb with a minimum of 55 volts during steady state operation.

For proper operation of the HID system, ensure the battery and the harness are capable of supplying up to 20 amps of current per ballast, with less than 2 volts of system loss or voltage drop. Each ballast requires up to 20 amps in order to ensure normal startup and run up of the lamp.

The range of white light that is acceptable is broad when compared to halogens. Therefore, some variation in headlight coloring between the right and left headlamp will be normal. Replace the arc tube only if the arc tube is determined to be at the bulb failure stage.

The intellibeam system operates the high beam headlamps ON and OFF automatically when certain conditions are met and the system is activated. The system consists of a digital light sensor that is located in a separate module that is mounted to the back of the inside rearview mirror. The digital sensor detects light, not vehicle movement. The sensor analyzes light color, intensity, and movement. The intellibeam system will turn OFF the high beam headlamps when other vehicles headlamps or taillights are detected by the digital sensor. Intellibeam can be deactivated when the headlamp dimmer switch is moved from the neutral position to the high beam or flash to pass (FTP) positions. When the headlamp dimmer switch is returned to the neutral position, intellibeam will be enabled.

Intellibeam modulates the high beam headlamps by gradually fading the high beam headlamps ON or OFF. Intellibeam is designed to ignore non-vehicular light sources. However, the system may dim the high beams if it detects lighting or lighting reflections similar in color and intensity to vehicle lighting. When this occurs, intellibeam will dim the high beams until the light or reflection source is no longer detected.

Important: Intellibeam may not operate properly if any of the following conditions exist:

Cleaning the intellibeam digital light sensor should be done periodically to ensure system performance. To clean the sensor, use glass cleaner and a soft cloth. Apply the glass cleaner to a soft cloth and gently wipe the light sensor lens. Do not apply the glass cleaner directly to the light sensor lens.

Important: The intellibeam system operates when the following conditions are met:

Speed Thresholds:

Important: The high beam indicator located on the instrument panel cluster (IPC) will turn ON as soon as the high beams are energized even thought full intensity has not been achieved. The high beam indicator will not turn OFF until the high beams have faded completely OFF.

Important: Enabling and disabling the intellibeam system can be achieved by performing the following:

The intellibeam demonstration mode allows the technician to verify that the intellibeam system components are operating correctly. Perform the intellibeam demonstration mode under daylight conditions only. The following steps detail how to enter the intellibeam demonstration mode.

1. Turn OFF the ignition.
2. While turning the ignition to the ON position, push and hold the intellibeam AUTO button located on the inside rearview mirror (ISRVM) for approximately 8 seconds after the ignition is turned ON. The high beam indicator located on the instrument panel cluster (IPC) will illuminate indicating the demonstration mode is enabled. The demonstration mode will run for approximately 45 seconds. The following actions will take place during the demonstration mode:

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High Beam Fading -- During this mode the high beams will fade from high to low 3 times. The high beam indicator located on the IPC will turn ON as soon as the high beams are energized even thought full intensity has not been achieved. The high beam indicator will not turn OFF until the high beams have faded completely OFF.

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Intellibeam Light Sensor Status -- During this mode, the intellibeam light sensor can be checked by covering the light sensor with a dark cloth. Once the light sensor if fully covered, the green LED intellibeam status indicator located on the left side of the ISRVM will turn OFF. When the light sensor is uncovered, the intellibeam status indicator will turn ON. This check will confirm that the intellibeam light sensor is operating correctly.

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Intellibeam Enable/Disable Status -- Intellibeam can indicate if the system is enabled or disabled. During the intellibeam light sensor check in step 2 above, if intellibeam is disabled, the green LED intellibeam status indicator will flash repeatedly once the light sensor is covered. Once the light sensor is uncovered, the green LED intellibeam status indicator will turn ON.

The instrument panel module (IPM) monitors the vehicle system voltage while in the RUN power mode. When the system voltage drops below 8.9 volts, the following will occur:

STAGE 1: If the low beam headlamps are ON, whether manually or automatically, the IPM will turn ON the high beam headlamps by activating the flash to pass output control and turn OFF the low beam headlamps.

When the system voltage drops below 8.5 volts, the following will occur:

If during the same ignition cycle the IPM enters either STAGE 1 or STAGE 2 operations noted above, the IPM determines that the system voltage has risen and the following will occur:

The Automatic Headlamp Leveling systems consist of the following components:

The automatic headlamp leveling system automatically maintains the vertical alignment of the headlamps when the vehicle load and driving conditions change. The headlamp leveling module receives inputs from the front and rear suspension position sensors to determine vehicle pitch. The suspension position sensors send an output to the headlamp leveling module as the vehicle suspension compresses and rebounds. The headlamp leveling module calculates the difference in vehicle pitch and sends a command to the headlamp leveling actuators. The headlamp leveling actuators drive the headlamps to the position commanded by the headlamp leveling module. The headlamp leveling system also monitors the performance of the high intensity discharge (HID) bulb and ballast. When the headlamp switch is placed in the ON position the headlamps will go down, and then back up to the center position.

The daytime running lamps (DRL) consist of the front turn signal lamps illuminated continuously. The DRLs will operate when the following conditions are met:

When conditions for DRL operation exist, the powertrain control module (PCM) sends a message via GMLAN serial data to the instrument panel module (IPM) indicating the transmission has been removed from the PARK position. The ambient light sensor is a light sensitive transistor that varies its voltage signal to the HVAC control module in response to changes to the outside (ambient) light level. When the HVAC control module receives this signal, it communicates via GMLAN with the IPM. The IPM either turns on the right and left front turn signals for DRL operation or the low beam headlamps for auto headlamp operation depending on outside lighting conditions. Any function or condition that turns the headlamps ON will cancel the DRLs operation.

The daytime running lamps (DRL) consist of the right and left low beam headlamps illuminated continuously and the park lamps. The DRLs will operate when the following conditions are met:

When conditions for DRL operation exist, the powertrain control module (PCM) sends a message via GMLAN serial data to the instrument panel module (IPM) indicating the transmission has been removed from the PARK position. The ambient light sensor is a light sensitive transistor that varies its voltage signal to the HVAC control module in response to changes to the outside (ambient) light level. When the HVAC control module receives this signal it communicates via GMLAN with the IPM. The IPM either turns ON the DRLs using a reduced output or the low beam headlamps at full intensity for auto headlamp operation. Any function or condition that turns the headlamps ON will cancel the DRLs operation. The DRLs consists of the low beam headlamps. With the headlamp switch in the OFF position, the headlamps will either be turned ON or OFF, after an approximate 8 second delay depending on whether daylight or low light conditions are sensed.

Twilight sentinel is a driver convenience that controls the exterior lamps in response to changes to the outside, ambient light level. The twilight sentinel will also keep the low beam headlamps and park lamps ON for a pre-selected period of time after the ignition is turned to the OFF position when night time conditions are sensed. The twilight delay is programmable through the driver information center (DIC) for Driver 1 and Driver 2.

The DIC will enable the park/headlamp delay feature under the following conditions:

The delay timer starts once the ignition is turned OFF. The lights will not turn OFF until the set time has been completed or the keyless entry system receives a request for door unlock or trunk release.

With the ignition switch in the ON or START position, the front fog lamps will illuminate when the driver toggles the front fog lamp switch to the ON position. The front fog lamp switch is a momentary switch that requires the driver to briefly place the front fog lamp switch to the ON position and release it. The instrument panel module (IPM) controls the front fog lamp relay coil. When the driver toggles the front fog lamp switch to the ON position, the switch supplies ground to the front fog lamp switch signal circuit of the IPM. In response to this input, the IPM supplies ground to the front fog lamp relay control circuit. The underhood fuse block supplies battery positive voltage to the switch circuit of the front fog lamp relay. Ignition voltage is available to the front fog lamp relay coil when the key is in the RUN or CRANK positions. When the IPM grounds the front fog lamp relay control circuit the relay coil energizes, closing the switch contacts. Current then flows from the fog lamp fuse through the front fog lamp relay switch to both front fog lamps. Both front fog lamps are permanently grounded at G104. The front fog lamps will default to the OFF position upon a key cycle.

The IPM will turn the park lamps ON when the front fog lamps are ON and send a message via GMLAN serial data to the instrument panel cluster (IPC) to enable the front fog lamp indicator. The front fog lamps will deactivate when either the flash-to-pass or the high beam headlamps are turned ON. For vehicles exported to Japan or any European Country except Norway or Sweden, the front fog lamps will remain illuminated with the operation of the high beam headlamps or flash-to-pass.

Rear fog lamps are required equipment on some export vehicles. The rear fog lamps are located in the rear deck lid lamp assembly. The rear fog lamps will only operate when the ignition in the RUN or CRANK positions and either the front fog lamps or headlamps are turned ON. When the driver turns the rear fog lamp switch ON, the switch supplies ground to the rear fog lamp switch signal circuit of the instrument panel module (IPM). In response to this input, the IPM sends a message via GMLAN serial data to the rear integration module (RIM). The RIM responds to this message by grounding the rear fog lamp relay control circuit. When the rear fog lamp relay control circuit is grounded, this energizes the rear fog lamp relay coil causing the switch side contacts to close. Supply voltage from the rear fog lamp fuse flows through the rear fog lamp relay switch to the rear fog lamps. The rear fog lamps have permanent ground at G401. The IPM communicates via GMLAN serial data with the instrument panel cluster (IPC) requesting the rear fog lamp indicator be illuminated. The rear fog lamps will deactivate if the front fog lamps or headlamps are turned OFF, if the ignition is out of the RUN or CRANK position, or if the driver turns the rear fog lamp switch OFF. The rear fog lamps will default to the OFF position upon a key cycle.

The tail, stop, and turn signal functions are performed by the quarter mounted tail lamps. The quarter mounted tail lamps consist of red lenses and light emitting diodes (LED) instead of incandescent bulbs. The tail lamp assemblies wrap around the corners of the vehicle and serve as the rear side marker. The lower portion of each lamp contains reflectors to alert approaching vehicles for night time driving safety. The park, tail, license, and marker lamps are turned ON when the headlamp switch is placed in the park lamp or headlamp position or anytime the headlights are requested. The park lamps are also turned ON with the front fog lamps. When the ignition switch is in the ON position, the instrument panel module (IPM) provides ground to the controlled voltage circuit of the park lamp relay coil. The underhood fuse block supplies battery positive voltage to the switch contacts of the park lamp relay. When the headlamp switch is placed in the park lamp or headlamp positions, the park lamp switch ON signal circuit is provided ground at G200. In response to this signal, the IPM provides ground to the control circuit of the park lamp relay coil, which energizes the relay coil. When the park lamp relay coil is energized, the relay switch contacts close causing current to flow from the park lamp relay to the LIC/Dimming fuse, LT PARK fuse, and to the RT PARK fuse. From these fuses, current flows to the park lamps, license lamps, side marker lamps, and tail lamps. The front park lamps and side marker lamps are grounded at G104. The tail lamps and rear sidemarker lamps are grounded at G401 and G402. The LIC/dimming fuse supplies battery positive voltage to the license lamps and IPM instrument panel lamp fuse supply voltage circuit for interior lamps dimming. The license lamps are grounded at G402. The inadvertent power control feature prevents the park lamps from remaining on more than 10 minutes if left ON. If the park lamps are turned ON after the ignition switch has been turned OFF, or is in the ACCY position, they will remain ON until turned OFF or the battery runs dead.

The position lamps are on export vehicles only. European countries require that side position lamps are activated when the vehicle is parked along the side of the road. This feature utilizes the front and rear park and the side marker lamps. The position lamp function operates only when the key is in the OFF position and the gear selector is in the PARK position. The position lamp function will operate when the turn signal switch is placed in the right turn position for the right side position lamps to illuminate or the left turn position for the left side position lamps to illuminate. Battery positive voltage is supplied to the standing lamp relay coil and switch. Battery positive voltage is supplied through the normally closed relay contacts of the standing lamp relay switch to each position lamp relay coil. Battery positive voltage is supplied to each position lamp relay switch. When the driver places the turn signal lever in the right or left turn position, the turn signal switch grounds the respective position lamp relay control circuit. This energizes the relay coil, closing the switch contacts providing battery voltage to the respective park and side marker lamps. When the gear selector is out of the PARK position, the rear integration module (RIM) grounds the standing lamp relay coil which removes battery positive voltage from each position lamp relay coil.

The brake pedal position (BPP) sensor is used to sense the action of the driver application of the brake pedal. The BPP sensor provides an analog voltage signal that will increase as the brake pedal is applied. The instrument panel module (IPM) provides a low reference signal and a 5-volt reference voltage to the BPP sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the IPM will apply battery voltage to the center high mounted stop lamp (CHMSL), transmission control module (TCM), engine control module (ECM), and stop lamp relay. When the stop lamp relay receives battery voltage from the IPM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the stop lamps fuse to illuminate the stop lamps. Ground for the left stop lamp and CHMSL is provided at G402 and the right stop lamp is grounded at G401. The stop lamps consist of red lenses and light emitting diodes (LED) instead of incandescent bulbs. The stop lamps on this vehicle will not illuminate unless the ignition is in the accessory, run, or crank positions. When the ignition is in the OFF position, the stop lamps will not illuminate when the brake pedal is applied.

With the ignition switch in the RUN position, the turn signal lamps will illuminate when the driver places the turn signal switch in the right or left positions. The instrument panel module (IPM) monitors the signal circuit of the turn signal/multifunction switch. The IPM relays the turn signal switch status to the rear integration module (RIM) via the GMLAN serial data circuit. The RIM uses the status of the turn signal switch to command the turn signals ON and OFF. The RIM controls both front and rear turn signals. The IPM also sends a message via GMLAN to the instrument panel cluster (IPC) to enable the turn signal indicators located in the IPC ON and OFF depending on the position of the turn signal switch. Voltage is supplied to the front and rear turn signals by the RIM. Ground is provided to the front turn signals at G104. The rear turn signals are grounded at G401 and G402. The turn signal/multifunction switch is grounded at G200. The rear turn signal functions are performed by the quarter mounted tail lamps. The rear turn signal lamps consist of red lenses and light emitting diodes (LED) instead of incandescent bulbs.

The hazard flashers may be activated in any power mode. The instrument panel module (IPM) monitors the signal circuit of the hazard switch. When the hazard switch is placed in the ON position, the switch contacts close and battery positive voltage from the IPM flows through the hazard switch to G201. The rear integration module (RIM) turn lamp supply voltage circuit is also provided with ground through the hazard switch when the contacts close at G201 which in turn illuminates the hazard switch LED. The RIM uses the status of the hazard switch to command the turn signals ON and OFF. The RIM controls both front and rear turn signals. The IPM sends a message via GMLAN to the instrument panel cluster (IPC) to enable both turn signal indicators in an ON and OFF duty cycle when the hazard switch is placed in the ON position. Voltage is supplied to the front and rear turn signals by the RIM. Ground is provided to the front turn signals at G104. The rear turn signals are grounded at G401 and G402.

The repeater lamps are located on the side of the front fender. The repeater lamps are used as additional turn signal lamps, and operate as described in the Turn Signal Lamps description. The repeater lamps are hard wired to there respective front turn signals and receive ground at G104.

The left rear fuse block supplies battery positive voltage through the REVERSE LAMP fuse to the coil and switch terminals of the reverse lamp relay. The instrument panel module (IPM) sends a power mode message to the rear integration module (RIM) indicating that the ignition is in the RUN position. When the driver places the gear selector in the REVERSE position, the powertrain control module (PCM) sends a message via GMLAN serial data to the RIM. The RIM provides ground to the reverse lamp relay control circuit which energizes the reverse lamp relay coil. With the reverse lamp relay coil energized, the relay switch contacts close and allow battery positive voltage to flow from the REVERSE LAMP fuse through the relay switch to illuminate the backup lamps. The backup lamps are permanently grounded at G402.

To provide battery run down protection, the exterior lamps will be deactivated automatically under certain conditions. The instrument panel module (IPM) monitors the state of the turn signal/multifunction switch. If the park or headlamp switch is ON when the ignition switch is placed in either the CRANK or RUN position and then placed in the OFF position, the IPM initiates a 10-minute timer. At the end of the 10 minutes, the IPM will turn OFF the control power output to the park and headlamp relay coils, deactivating the exterior lamps. This feature will be cancelled if any power mode other than OFF becomes active. The IPM will disable battery run down protection if any of the following conditions exist. The park or headlamp switch is placed in the ON to OFF position, and back to the ON position during battery run down protection. The IPM determined that the park or headlamp switch was not active when the ignition was turned OFF.