The exterior lighting consist of the following lamps:

The headlamps may be turned ON in 2 different ways:

Battery voltage is applied at all times to the coil and switched side of the low beam relay. Ground is applied at all times from G201 to the turn signal/multifunction switch. When the turn signal/multifunction switch is placed in the HEAD position, ground is applied from the turn signal/multifunction switch through the headlamps ON signal circuit to the body control module (BCM). The BCM applies ground to the headlamp low beam relay control circuit. This energizes the low beam relay, closing the switched side and applies battery voltage to the LEFT and RIGHT LOW BEAM fuses. Battery voltage is then applied from the fuses, through the low beam voltage supply circuits to the ballast in the headlamp assembly. When battery voltage is applied to the headlamp ballast through the low beam voltage supply 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.

Ground is applied from G101 for the left headlamp and G102 for the right headlamp.

Battery voltage is applied at all times to the coil and switched side of the high beam relay. Battery voltage is also applied at all times through the coil side of the low beam relay to the low beam relay control circuit, to the turn signal/multifunction switch. When the turn signal/multifunction switch is placed in the high beam position, battery voltage is applied through the headlamp switch high beam signal circuit to the body control module (BCM). The BCM applies ground to the headlamp high beam relay control circuit. This energizes the high beam relay, closing the switched side contacts, applying battery voltage to the Left and Right High Beam Fuses. Battery voltage is then applied from the High Beam Fuses through the high beam voltage supply circuits to the left and right high beam headlamps.

Ground is applied from G101 for the left high beam headlamp and G102 for the right high beam headlamp.

Run Up Of The Lamp

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.

When To Change The HID Bulb

Bulb failure, 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-hour period. When the bulb begins shutting itself off occasionally, the ballast will automatically turn the bulb back on again within 0.5 seconds. The ballast will re-strike 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 excessive, repetitive current input . Repetitive and excessive restarts or re-strikes, without time for the ballast to cool down, will permanently damage the ballast. As a safeguard, when repetitive re-strikes are detected, the ballast will not attempt to re-strike the lamp. The ballast then shuts down and the bulb goes out.

The following symptoms are noticeable signs of bulb failure:

Input power to the ballast must be terminated in order to reset the ballast's 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 excessive, repetitive bulb re-strikes. When excessive, repetitive bulb re-strikes 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.

Bulb failures are often sporadic at first, and difficult to repeat. Technicians can identify bulb failure by observing if the problem gets progressively worse over the next 100 hours of operation.

Light Color

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 high intensity discharge (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 failure stage.

Place the turn signal/multifunction switch in the OFF position for automatic lamp control. During automatic lamp control the headlamps will be off during daylight conditions but will turn on when the ambient light sensor detects low outside light level. The ambient light sensor is a light sensitive transistor that varies the voltage signal to the HVAC control module. The HVAC control module sends a signal to the body control module (BCM) via class 2 serial data commanding the BCM to apply ground to the headlamp low beam relay control circuit. This energizes the low beam relay, closing the switched side and applies battery voltage to the LEFT and RIGHT LOW BEAM fuses. Battery voltage is applied from the low beam fuses, through the low beam voltage supply circuits to the ballast in the headlamp assembly. When battery voltage is applied to the headlamp ballast through the low beam voltage supply circuits, the ballast will then 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. The ground for the headlamps is supplied from G101 for the left headlamp and G102 for the right headlamp.

When the low beam headlamps are on and the turn signal/multifunction switch is momentarily placed in the flash to pass (FTP) position, ground is applied from G201 to the turn signal/multifunction switch. The turn signal/multifunction switch applies ground to the body control module (BCM) through the FTP switch signal circuit. The BCM then applies ground to the high beam relay control circuit. This energizes the high beam relay, closing the switched side 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 solenoid switched voltage supply circuit to the high beam solenoid assembly inside of the headlamp. This causes the solenoid to retract a plate partially covering the low beam headlamps and allowing the lamps to illuminate at full brightness momentarily.

The daytime running lamps (DRL) will illuminate the right and left front turn signal bulbs continuously. The DRLs will operate when the following conditions are met:

1. The ignition is in the RUN or CRANK position
2. The shift lever is out of the PARK position for vehicles equipped with automatic transmissions or the parking brake is released for vehicles with manual transmissions.
3. The high and low beam headlamps are OFF.

The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between .2 and 4.9 volts depending on outside lighting conditions. The HVAC control module provides a low reference ground and a 5-volt reference signal to the ambient light sensor. The HVAC control module monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. The HVAC control module sends a signal to the body control module (BCM) via class 2 serial data commanding the BCM to turn the front turn lamps on steady (non-flashing). Any function or condition that turns on the headlamps will cancel the DRL operation. With the turn signal/multifunction switch in the OFF position, the turn signal lamps will either be turned ON or OFF after a 30-second delay, depending on whether daylight or low light conditions are sensed by the ambient light sensor.

Ground is applied at all times at G201 to the front fog lamp switch inside of the turn signal/multifunction switch. When the front fog lamp switch is placed in the ON position, ground is applied through the front fog lamp switch signal circuit to the body control module (BCM). The BCM applies battery voltage through the front fog lamp relay control circuit to the coil side of the fog lamp relay. Battery voltage is applied at all times from the FRT FOG LP fuse to the switch side of the FRT FOG LP relay. When the relay is energized, the relay switch contacts close and allow battery voltage to be applied from the FRT FOG LP fuse, through the relay switch contacts, to the front fog lamps. Ground for the front fog lamps is applied at all times at G101 for the left fog lamp and G102 for the right fog lamp. G102 also serves as ground for the coil side of the FRT FOG LP relay.

Ground is applied at all times at G201 to the rear fog lamp switch inside of the turn signal/multifunction switch. When the rear fog lamp switch is placed in the ON position, ground is applied through the rear fog lamp switch signal circuit to the body control module (BCM). Battery voltage is applied at all times from the REAR FOG/ALDL TOP SW fuse to the BCM. The BCM applies battery voltage through the rear fog lamp relay control circuit to activate the rear fog lamp relay located in the I/P relay block. When the relay is activated, the switch closes and allows battery voltage to be applied from the RR FOG/ALDL TOP SW fuse, through the relay, to the rear fog lamps. Ground for the rear fog lamps is applied at all times at G302.

Battery voltage is applied at all times from the PK LAMPS fuse to both coil and switched sides of the PARK LAMP Relay located in the underhood fuse block. Ground is applied at G201 to the turn signal/multifunction switch at all times. When the headlamp switch is place in either the HEAD or PARK position, ground is applied to the park lamp relay control circuit. This energizes the PARK LAMP Relay and applies battery voltage to all park, tail, license, and marker lamps. Ground for the front park and marker lamps is supplied at G101 for the left and G102 for the right. Ground for the license, tail, and rear side marker lamps is supplied at G302.

Ground is applied at all times at G201 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 body control module (BCM) through either the right turn or left turn signal switch circuit. Battery voltage is applied at all times from the BATT MAIN 3 fuse to the BCM. The BCM then applies a pulsating voltage to the front and rear turn signal lamps. Ground for the left front turn signal lamp is supplied at G101. Ground for the right front turn signal lamp is supplied at G102. The left and right rear turn signal lamps are supplied ground at G302.

The hazard flashers may be activated in any power mode. The hazard switch is permanently grounded through G201. When the hazard switch is placed in the ON position, ground is applied through the hazard switch signal circuit to the body control module (BCM). The BCM supplies battery voltage to all four turn signal lamps in an ON and OFF duty cycle. When the hazard switch is placed in the ON position, the instrument panel cluster (IPC) receives a signal from the hazard switch and applies voltage through the hazard flash indicator circuit to the hazard switch to illuminate the hazard indicator.

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 body control module (BCM) provides a low reference signal and a 5-volt 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 positive voltage to the stop lamps, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL). Ground for the stop lamps and CHMSL is applied at G302. 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.

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 G101 for the left front repeater lamp and ground G102 for the right front repeater lamp.

The underhood fuse block supplies battery voltage through the STOP/B/U/ LPS fuse to the coil and switch terminals of the REVERSE LAMP Relay located in the body control module (BCM). When the transmission is placed in the REVERSE position, the transmission control module (TCM) sends a class 2 message to the BCM. The message indicates that the gear selector is in the REVERSE position. The BCM grounds the back up lamp relay control circuit of the reverse lamp relay . This energizes the reverse lamp relay, closing the switch side contacts and provides battery voltage to the REVERSE LAMPS fuse through to the backup lamps. The backup lamps are permanently grounded at G302. With both power and ground the backup lamps illuminate. Once the driver moves the gear selector out of the REVERSE position, a message is sent by the TCM via class 2 serial data requesting the BCM to remove ground from the REVERSE LAMP Relay control circuit. This opens the REVERSE LAMP Relay switch contacts turning OFF the backup lamps.