The exterior lighting system consist of the following lamps:

• Automatic High Beam Assist
• Backup Lamps
• Daytime Running Lamps
• Front Fog Lamps
• Hazard Warning Lamps
• Headlamps
• Park, Tail, License and Side Marker Lamps
• Repeater Lamps
• Stop Lamps
• Turn Signal Lamps

The headlamps may be turned ON in 3 different ways:

• When the headlamp switch is placed in the ON position, for normal operation
• When the headlamp switch is placed in the AUTOMATIC LIGHT position, for automatic lamp control
• When the headlamp switch is placed in the AUTOMATIC LIGHT position, with the windshield wipers ON in daylight conditions, after a 6 s delay

The BCM controls the headlamps based on the inputs explained above. When a low beam request is received, the BCM supplies B+ to the low beam headlamps, illuminating the low beam headlamps.

When the BCM commands the low beam headlamps ON, the operator will notice the interior backlighting for the instrument cluster and the various other switches dim to the level of brightness selected by the instrument panel dimmer switch.

The body control module (BCM) monitors three signal circuits from the turn signal/multifunction switch. When the turn signal/multifunction switch is in the AUTO position, all three signal circuits are open. When placed in the AUTO position, the BCM monitors inputs from the ambient light sensor to determine if headlamps are required or if daytime running lamps will be activated based on outside lighting conditions. When the turn signal/multifunction switch is placed in the OFF position, the turn signal/multifunction switch headlamps OFF signal circuit is grounded, indicating to the BCM that the exterior lamps should be turned OFF. With the turn signal/multifunction switch in the PARK position, the turn signal/multifunction switch park lamps ON signal circuit is grounded, indicating that the park lamps have been requested. When the turn signal/multifunction switch is placed in the HEADLAMP position, both the turn signal/multifunction switch park lamps ON signal circuit and the turn signal/multifunction switch headlamps ON signal circuit are grounded. The BCM responds to the low beam request by applying ground to the low beam control circuits. Battery voltage is then applied through the low beam control circuits to the left and right headlamp ballast located in each headlamp assembly. When battery voltage is applied to the headlamp ballast through the low beam control circuits, the ballast charge the starter to start the lamp. High intensity discharge (HID) headlamps do not have filaments like traditional bulbs, instead the starter uses a high voltage transformer to convert the input voltage into a higher voltage. This increased voltage is used in order to create an arc between the electrodes in the bulb.

Each ballast requires higher amperage in order to ensure normal startup and run up of the lamp. Run up is the term used to describe the extra power level given to the bulb. The input current during the steady state operation is lower that the start up amperage. After the lamp receives the strike from the starter and the arc is established, the ballast uses its operating voltage in order to provide the run up power needed in order to keep the lamp ON. The lamp rapidly increases in intensity from a dim glow to a very high-intensity, bright light called a steady state. Within a few seconds of the arc being established in the bulb, the majority of steady state is complete. 100 percent of the steady state is completed shortly there after. A high watt power level is necessary in order to bring the lamp to a steady state in such a short period of time. The high watt power level allows the lamp to meet the SAE light vs. time specification.

An inoperative bulb, end of life occurs when the bulb gets old and becomes unstable. The bulb may begin shutting itself OFF sporadically and unpredictably at first, perhaps only once during a 24 h period. When the bulb begins shutting itself off occasionally, the ballast will automatically turn the bulb back ON again within 0.5 s. The ballast will restrike the bulb so quickly that the bulb may not appear to have shut off. As the bulb ages, the bulb may begin to shut off more frequently, eventually over 30 times per minute. When the bulb begins to shut off more frequently, the ballast receives an extreme amount of repetitive current input . Repetitive and extreme amount restarts or restrikes, without time for the ballast to cool down, will permanently damage the ballast. As a safeguard, when repetitive restrikes are detected, the ballast will not attempt to restrike the lamp. The ballast then shuts down and the bulb goes out.

The following symptoms are noticeable signs of an inoperative bulb:

• Flickering light, caused in the early stages of an inoperative bulb
• Lights go out, caused when the ballast detects, repetitive bulb restrike
• Color change – The lamp may change to a dim pink glow.

Input power to the ballast must be terminated in order to reset the ballasts fault circuitry. In order to terminate the input power to the ballast, turn the lights OFF and back ON again. Turning the lights OFF and back ON again resets all of the fault circuitry within the ballast until the next occurrence of an extreme amount of repetitive bulb restrike. When an extreme amount of repetitive bulb restrikes occur, replace the starter/arc tube assembly. The ballast will begin the start-up process when the starter/arc tube assembly is replaced. Repeatedly resetting the input power can overheat the internal components and cause permanent damage to the ballast. Allow a few minutes of cool-down time in between reset attempts.

Inoperative bulbs are often sporadic at first, and difficult to repeat. Inoperative bulbs can be identified by observing if the condition gets progressively worse over the next 100 h of operation.

White light has a different color rating than regular headlamps. 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. One HID at the end of the normal range may appear considerably different in color from one at the other end of the range. Difference in color is normal. Replace the arc tube only if the arc tube is determined to be at the bulb inoperative stage.

The headlamps may be turned ON in 3 different ways:

• When the headlamp switch is placed in the ON position, for normal operation
• When the headlamp switch is placed in the AUTOMATIC LIGHT position, for automatic lamp control
• When the headlamp switch is placed in the AUTOMATIC LIGHT position, with the windshield wipers ON in daylight conditions, after a 6 s delay

The BCM controls the headlamps based on the inputs explained above. When a low beam request is received, the BCM supplies B+ to the left and right headlamp control modules, which illuminate the low beam LEDs.

When the BCM commands the low beam headlamps ON, the operator will notice the interior backlighting for the instrument cluster and the various other switches dim to the level of brightness selected by the instrument panel dimmer switch.

No parts are serviceable within the headlamp assemblies so complete headlamp assembly replacement is necessary.

When the low beam headlamps are ON and the turn signal/multifunction switch is placed in the high beam position, ground is applied to the BCM through the high beam signal circuit. The BCM responds to the high beam request by applying ground to the high beam relay control circuit which energizes the high beam relay. With the high beam relay energized, the switch contacts close allowing battery voltage to flow through the left and right high beam fuses to the high beam control circuits and on to the left and right high beam solenoid actuators within the headlamp assemblies. Once the high beam solenoid actuators are active, the solenoid shutters open in each headlamp assembly exposing the remaining portion of the headlamp that was covered by the shutters illuminating the high beams at full intensity.

When the low beam headlamps are ON and the turn signal/multifunction switch is placed in the high beam position, ground is applied to the BCM through the high beam signal circuit. The BCM responds to the high beam request by applying ground to the high beam relay control circuit which energizes the high beam relay. With the high beam relay energized, the switch contacts close allowing battery voltage to flow through the left and right high beam fuses to the high beam control circuits and on to the left and right headlamp control modules within the headlamp assemblies. When supplied with battery voltage, the left and right headlamp control modules will illuminate the high beam LEDs.

No parts are serviceable within the headlamp assemblies so complete headlamp assembly replacement is necessary.

The automatic high beam assist (IntelliBeam) system operates the high beam headlamps ON and OFF automatically when the system is activated and certain conditions are met. The IntelliBeam system consists of a front camera module that detects light and is able to identify approaching vehicles on an even, straight road at a distance of greater than 0.4 km (0.25 mi). The front camera module analyzes light color, intensity, and movement. The IntelliBeam system will turn OFF the high beam headlamps when approaching vehicle headlamps or preceding vehicle taillights are detected by the front camera module. 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. IntelliBeam can be reactivated by operating the high beam select switch from the neutral position to the high beam position twice within 2 seconds.

• Vehicle ON
• Headlamp switch placed in the AUTO position
• Press the Auto High Beam ON/OFF switch located on the turn signal/multifunction switch
• Headlamp dimmer switch must be in the neutral position
• Outside lighting conditions must be dark
• Vehicle speed greater than 25 mph (40 km/h)

The following are conditions that the IntelliBeam system will turn the high beam headlamps off during operation:

• The system detects approaching traffic headlamps
• The system detects preceding traffic tail lamps
• Ambient light level too high due to towns or twilight situations
• The vehicle’s speed drops below 13 mph (22 km/h)
• Delay

• Approaching and preceding vehicles lamps are undetectable due to dirt, snow, road spray, smoke, fog, or any other airborne conditions.
• The front camera module is covered with ice, dirt, snow, haze, or is obstructed.
• The vehicle is being driven on winding or hilly road conditions which would make any on coming vehicle headlamps undetectable by the IntelliBeam.

• Manually operating the headlamp dimmer switch from neutral to high beam position
• Press the Auto High Beam ON/OFF switch located on the turn signal/multifunction switch
• IntelliBeam is deactivated automatically when the front or rear fog lamps are turned ON

The status of the IntelliBeam system is shown by a green indicator located on the instrument panel cluster. When IntelliBeam is active, the indicator will be illuminated continuously. If the operator deactivates the IntelliBeam system, the indicator will turn off.

When the turn signal/multifunction switch is momentarily placed in the flash to pass position, ground is applied to the turn signal/multifunction switch. The turn signal/multifunction switch applies ground to the body control module (BCM) through the flash to pass switch signal circuit. The BCM responds to the flash to pass request by applying ground to the high beam relay control circuit. This energizes the high beam relay, closing the switch side contacts of the high beam relay, applying battery voltage to the left and right high beam fuses. Battery voltage is applied from the high beam fuses through the high beam control circuit to the high beam control circuits and on to the left and right high beam solenoid actuators within the headlamp assemblies. Once the high beam solenoid actuators are active, the solenoid shutters open in each headlamp assembly exposing the remaining portion of the headlamp that was covered by the shutters illuminating the high beams at full intensity.

The daytime running lamps are combined with the park lamps. The daytime running lamps will operate when the following conditions are met:

• Engine is running.
• Headlamp switch in AUTOMATIC LIGHT position.
• The high and low beam headlamps are OFF.

The rain/ambient light sensor module is used to monitor outside lighting conditions. The rain/ambient light sensor module provides a serial data message to the BCM based on outside lighting conditions to determine if outside lighting conditions are correct for either daytime running lamps or automatic lamp control when the headlamp switch is in the AUTO position. In daylight conditions the BCM will command the designated daytime running lamps ON. During low light conditions the BCM will command the low beam headlamps ON. Any function or condition that turns on the headlamps will cancel daytime running lamps operation.

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 V depending on outside lighting conditions. The body control module (BCM) provides a 5 V reference signal to the ambient light sensor and the HVAC control module provides a low reference ground. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lamps or automatic lamp control when the headlamp switch is in the AUTO position. In daylight conditions the BCM will command the daytime running lamps ON. During low light conditions the BCM will command the low beam headlamps ON. Any function or condition that turns on the headlamps will cancel daytime running lamps operation.

In daylight conditions, the BCM will command the daytime running lamps ON by supplying B+ to the daytime running lamps control circuit, illuminating the left and right daytime running lamp LEDs. Any function or condition that turns on the headlamps will cancel daytime running lamps operation. No daytime running lamp parts are serviceable within the headlamp assemblies so complete headlamp assembly replacement is necessary.

The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the front fog lamp fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps.

The park lamps, tail lamps, and license plate lamps are turned ON when the headlamp switch is placed in the PARK, AUTO, or LOW BEAM position. When the BCM receives a request from the headlamp switch to turn ON the park lamps the BCM applies ground to the park lamps relay control circuit, which energizes the park lamps relay. With the park lamps relay energized, the switch contacts close allowing battery voltage to flow through the left and right park lamp fuses to the park lamp control circuits illuminating left and right park, side marker, and tail lamps.

Ground is applied at all times to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the BCM through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through there respective voltage supply circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument cluster requesting the respective turn signal indicator be pulsed ON and OFF.

The hazard warning lamps may be activated in any power mode. The hazard switch is permanently grounded. When the hazard switch is placed in the ON position, ground is applied through the hazard switch signal circuit to the BCM. The BCM supplies battery voltage to all turn signal lamps in an ON and OFF duty cycle. When the hazard switch is activated, the BCM sends a serial data message to the instrument cluster requesting both turn signal indicators to be cycled ON and OFF.

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The BCM provides a low reference signal and a 5 V reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop lamp control circuit and center high mounted stop lamp control circuit. When the control circuit is energized the stop lamps are illuminated.

When the transmission is placed in the reverse position, the engine control module (ECM) sends a serial data message to the BCM. The message indicates that the gear selector is in the reverse position. The BCM applies battery voltage to the backup lamps. The backup lamps are permanently grounded. Once the driver moves the gear selector out of the reverse position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the backup lamp control circuit.

To provide battery run down protection, the exterior lamps will be deactivated automatically under certain conditions. The BCM monitors the state of the headlamp 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 BCM initiates a 10 min timer. At the end of the 10 min, the BCM 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 BCM 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 BCM determined that the park or headlamp switch was not active when the ignition was turned OFF.