Lighting Systems - Introduction: Other Cadillac STS I

Aiming Area Preparation

Choose an appropriate aiming area, then prepare the aiming screen

1. The aiming area should be darkened and large enough to accommodate the vehicle and an additional 7.62 m (25 ft) measured from the face of the headlamp capsules to the front of the screen.
2. The floor on which the vehicle rests must be flat with the bottom of the screen.
3. The aiming screen should be at least 1.52 m (5 ft) high by 3.66 m (12 ft) wide with a matte white surface well shaded from extraneous light, and properly adjusted to the floor on which the vehicle stands. The screen should be provided with a vertical centerline (3), 2 laterally adjustable vertical tapes (2), and one vertically adjustable horizontal tape (1).
4. The screen must be movable to be aligned parallel with the rear axle of the vehicle. This will allow for a horizontal line drawn perpendicular to the centerline of the screen to pass through the center point between the 2 headlamp capsules (4).
5. After the aiming screen has been set up in a permanent location, paint or tape a reference line on the floor 7.62 m (25 ft) from the screen, to identify the proper location of the headlamp capsules (5) being aimed. If a regular commercial aiming screen is not available, use a vertical wall having a clear uninterrupted area at least 1.83 m (6 ft) high by 3.66 m (12 ft) wide, finished with a washable non-gloss white paint.

Vehicle Preparation

Prepare the vehicle for adjusting the headlamp beam aim

1. Verify that all the components are in place on the vehicle, if other service has been performed on the vehicle.
2. The vehicle must have a full tank of gas.
3. Verify that the tires are inflated to the proper pressures.
4. Stop all other work on the vehicle.
5. Position the vehicle squarely with the aiming screen and with the headlamp directly over the reference line which is painted or taped on the floor.
6. Locate the vertical center line on the aiming screen (3) to be in line with the center of the vehicle (4). This can be accomplished by sighting through the center of the rear window and over the hood. Mark the vertical center of the front and rear windows with narrow tape. Use these marks as sights to locate the centerline of the vehicle. Move the vehicle or the screen until the center line of the screen comes into alignment with the 2 points.
7. Close the doors.
8. Rock the vehicle sideways to stabilize the suspension.
9. Measure the height (6) from the floor to the aiming dots of the headlamps. Adjust the horizontal tape (1) on the aiming screen to match this dimension.
10. Measure the distance (5) between the headlamp aiming dots. Position the vertical tapes (2) this distance equally to the right and left of the centerline.

Headlamp Aiming Procedure

1. Open the hood.
2. Measure from the floor to the center of the headlamp bulb. Some headlamps have an aim dot marked on the headlamp lens.
3. At the screen, measure from the floor and place the horizontal tape at the measured distance.
4. Measure from the reference line on the floor to the left headlamp bulb centerline.
5. At the screen, measure from the reference line and place the vertical tape at the measured distance.
6. Measure from the reference line on the floor to the right headlamp bulb centerline.
7. At the screen, measure from the reference line and place the vertical tape at the measured distance.
8. Turn ON the low beam headlamps and block the light from projecting onto the screen from the passenger side headlamp.
9. Adjust the vertical aim of the headlamps to the specifications required by the state and the local authorities, or as shown in step 8.
10. Rotate the headlamp adjuster (1) to change the vertical aim of the headlamp.
11. Repeat the aiming procedure for the passenger side headlamp while blocking the light from projecting onto the screen from the driver side headlamp.
12. Close the hood.

Scheme 48

Fog Lamp Replacement - Rear

Fog Lamp Aiming Procedure

The front fog lamps must be aimed for proper illumination of the road. The aim should be verified when a when a new fog lamp assembly is installed, or if service or repairs in the front end area may have disturbed the fog lamp mounting surface.

No horizontal adjustment for aiming the front fog lamp assemblies is provided on this vehicle.

1. Use the headlamp aiming screen for aiming the fog lamps. Refer to «Headlamp Aiming»(ref-197547-S23610988312005101200000) .
2. To ensure accurate vertical front fog lamp aiming, first perform the following steps to prepare the vehicle: Ensure that all the components are in place on the vehicle. Ensure that the fuel tank is full. Ensure that the tires are inflated to the proper pressure. Place the vehicle on a level surface 7.6 m (25 ft) away from a target screen. Stop all other operations of work on the vehicle. Jounce the vehicle to settle the suspension. IMPORTANT: Do NOT cover the headlamps. This may cause excessive heat buildup. Block the headlamps from projecting light onto the aiming screen while aiming the fog lamps.
3. Turn the front fog lamps ON.
4. Measure the distance from the centerline of the vehicle (1) to the center of each fog lamp beam (3). These measurement should be the same. If necessary adjust the fog lamp mounting surface.
5. Measure from the center of the fog lamp to the ground line. Using this measurement, mark the horizontal centerline (2) of the fog lamp on the target screen directly in front of the vehicle.
6. The fog lamp vertical adjustment screw is located on the front of the fog lamp.
7. Adjust the fog lamp up or down until the top of the fog lamp beam (4) on the target screen is 102 mm (4 in) below the horizontal centerline (2).
8. Turn OFF the front fog lamps.

Exterior Lamps

The exterior lighting system consists of the following features

1. Backup lamps
2. Daytime running lamps (DRL)
3. Front fog lamps
4. Hazard lamps
5. Headlamps
6. Park, tail, license, and cornering/side marker lamps
7. Position lamps (Export)
8. Rear fog lamps (Export)
9. Repeater lamps
10. Stop lamps
11. Turn signal lamps

Headlamps

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

1. When the headlamp switch is placed in the ON position, for normal operation
2. When the headlamp switch is placed in the AUTO position, for automatic lamp control (ALC)
3. When the headlamp switch is placed in the AUTO position, with the windshield wipers ON in daylight conditions, after a 6-second delay

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

1. The ignition is in the RUN position.
2. The headlamps are currently OFF.
3. The headlamp switch is in the AUTO position.
4. The ambient light sensor indicates DAYTIME conditions.

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

Headlamps - High Intensity Discharge (HID)

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.

Headlamps - Intellibeam

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.

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

1. The other vehicles lamps are undetectable due to dirt, snow, road spray, smoke, fog, or any other airborne conditions.
2. The vehicle windshield is covered with ice, dirt, snow, haze, or the intellibeam digital light sensor is obstructed.
3. The vehicle ride height is such that the front of the vehicle is pointed upward causing the intellibeam light sensor to be aimed high.
4. The vehicle is being driven on winding or hilly road conditions which would make any on coming vehicle headlamps undetectable by the intellibeam.

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.

The intellibeam system operates when the following conditions are met

1. The headlamp switch is in the AUTO position.
2. The headlamp dimmer switch must be in the neutral position.
3. Intellibeam has been turned ON by pushing the ON/OFF button located on the face of the rearview mirror.
4. Outside conditions must be dark.
5. Intellibeam will only function when the vehicle is in DRIVE and moving. Speed Thresholds: Accelerating: As the vehicle is accelerating, intellibeam will gradually apply the high beams when vehicle speed reaches 20 MPH or greater. Full high beam intensity will not occur until the vehicle has achieved a speed of 25 MPH or greater. Decelerating: As the vehicle is decelerating, intellibeam will fade the high beams down until they are completely OFF at or below 15 MPH.

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

1. Intellibeam is automatically disabled each time the vehicle is started. To disable intellibeam after the system has been enabled, press the intellibeam ON/OFF button on the rearview mirror for 3 seconds and releasing it after the green LED intellibeam status indicator on the left side of the rearview mirror flashes 2 times. When this is done, the intellibeam system will not be active until the system is manually turned ON.
2. Intellibeam is enabled by pressing and releasing the intellibeam ON/OFF button located on the rearview mirror after the vehicle has been started. The green LED intellibeam status indicator located on the left side of the rearview mirror will flash 1 time to indicate the system has been turned ON.

Intellibeam Demonstration Mode

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 ON/OFF button located on the inside rearview mirror (ISRVM) for 6 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: 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. 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. 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.

Automatic Headlamp Leveling - Export Only

The Automatic Headlamp Leveling systems consist of the following components

1. Headlamp leveling module
2. Headlamp leveling actuator - left
3. Headlamp leveling actuator - right
4. Suspension position sensor - LF
5. Suspension position sensor - LR

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.

Daytime Running Lamps (DRL) - Domestic/Canadian

The daytime running lamps (DRL) consist of the front turn signal lamps illuminated 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.
3. The high and low beam headlamps are OFF.
4. The park brake is not applied.

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.

Daytime Running Lamps (DRL) - Norway/Sweden

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

1. The ignition is in the RUN or CRANK position.
2. The shift lever is out of the PARK position.
3. The high and low beam headlamps are OFF.
4. The park lamps are OFF.
5. The fog lamps are OFF.
6. The park brake is not applied.

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

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. Refer to Personalization Description and Operation in Personalization for more Driver 1 and Driver 2 information. The following delay settings are available to Driver 1 and Driver 2

1. 0 seconds
2. 15 seconds
3. 30 seconds
4. 60 seconds
5. 90 seconds
6. 120 seconds
7. 180 seconds
8. 240 seconds

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

1. The time delay is programed to 15 seconds or more for the current driver.
2. The headlamp switch is in the auto position.
3. The automatic headlamp feature has not been canceled.
4. The ambient light sensor status is night time.
5. The ignition is OFF.

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.

Front Fog Lamps

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 - Export

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.

Park, Tail, License, and Marker Lamps

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.

Position Lamps - Export

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.

Stop Lamps

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.

Turn Signal Lamps

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.

Hazard Flasher Lamps

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.

Repeater Lamps

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.

Backup Lamps

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.

Battery Run Down Protection/Inadvertent Power

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.

Interior Lamps

The interior lamps consist of 2 groups. The first group are those lamps which may not be dimmed. The second group include lamps that may be dimmed.

Courtesy/Illuminated Entry Lamps

Courtesy/illuminated entry lamps are lamps that may be illuminated by opening a door, manually operating a switch or through a remote control door lock receiver (RCDLR) command. This group consist of the following lamps

1. Door courtesy lamps
2. Footwell lamps
3. Illuminated entry lamps
4. Instrument panel (I/P) compartment lamps
5. Overhead console courtesy/reading lamps
6. Rear compartment lamps
7. Vanity mirror lamps

The rear integration module (RIM) controls battery positive voltage and ground to the interior courtesy lamps in the following manner. Battery positive voltage is supplied through the INTERIOR LAMP fuse to both the switch side and coil side of the interior lamp relay. The RIM provides a ground to the control circuit of the interior lamp relay during all power modes except when battery run down protection is active. With the interior lamp relay energized, battery positive voltage is supplied to all the interior lamps in this group. The ground side circuits of the door, footwell, and overhead courtesy lamps are controlled by a pulse width modulated (PWM) ground circuit of the RIM. The RIM pulses the on time of the ground circuit between 0-100 percent at a frequency of approximately 100 hertz. By decreasing the on time percentage of the controlled ground circuit the intensity of the lamps will decrease. This effect is called theater dimming. The RIM will illuminate these lamps under various conditions which will be described in the following information

Courtesy/Illuminated Entry

Courtesy/illuminated entry occurs when any of the door control modules receive a discrete input from the door open switch located in the door latch assembly. The appropriate door control module sends a GMLAN serial data message to the RIM indicating a door is opened. If the ambient light sensor status is dark, the RIM will illuminate the courtesy lamps. The lamps will remain illuminated for 25 seconds after all the doors are closed or until the ignition is placed in the ON position. At this time the RIM will fade the lamps from full intensity to OFF in 3-5 seconds by activating the theater dim feature.

Exit Lighting

Exit lighting is activated when the following conditions exists. The RIM receives a GMLAN serial data message from the instrument panel cluster (IPC) indicating that the ignition key has been removed from the lock cylinder, the ambient light sensor status is dark and all the doors are closed. At this time the RIM will illuminate the interior lamps. During this exit lighting feature, the RIM will also request that the driver door module (DDM) illuminate the driver door switch back lighting at full intensity. The RIM will theater dim the interior lamps after 20-25 seconds. If the key is place back into the lock cylinder before the lamps have dimmed, the RIM will immediately activate the theater dim feature.

Keyless Entry Illumination

Keyless entry illumination is activated when the RCDLR detects a door UNLOCK command from the keyless entry transmitter. The RCDLR will send a GMLAN serial data message to the RIM indicating an UNLOCK command was received. The RIM will activate the courtesy lamps if all the doors are closed, the ignition is in the OFF position, and the ambient light sensor status is dark. The RIM will also send a GMLAN serial data message to the DDM requesting the driver door switches to be illuminated at full intensity. The RIM will keep the lamps illuminated 36-40 seconds and then turn them OFF through the theater dimming feature. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either to the ON or RUN positions the courtesy lamps will deactivate immediately.

Manual Interior Lighting

The interior lamps may also be illuminated manually in all ambient light conditions. When a vehicle occupant places the driver information center (DIC)/dimmer switch to the interior lamp ON position, the contacts in the switch close grounding the interior lamp input circuit of the instrument panel module (IPM). With this input grounded, the IPM sends a GMLAN serial data message to the RIM requesting the interior lamps illuminate. The RIM will ground the lamps as mentioned above. When the I/P dimmer switch is placed out of the interior lamp ON position, the RIM will immediately turn OFF the interior lamps.

Panic Illumination

If the RCDLR detects a panic signal from keyless entry transmitter, the RIM will activate the interior lamps and request the DDM to illuminate the driver door switch back lighting at full intensity. The interior lamps will remain illuminated for 30 seconds or until the RCDLR detects a door UNLOCK message. At this time the RIM will active the theater dim feature.

Reading Lamps

The reading lamps will operate in all ambient light conditions. The reading lamp switches are located in the courtesy/overhead reading lamp assemblies. By pressing the overhead reading lamp switch the contacts in the switch close and provides a direct path to ground for the corresponding reading lamp. When the switch is pressed again, the contacts open turning OFF the reading lamp.

Rear Compartment Lamp

The rear compartment lamp will operate in all ambient light conditions. When the rear deck lid opens, the rear compartment lamp switch in the latch assembly closes to provide a direct path to ground for the rear compartment lamp. Closing the deck lid opens the contacts in the switch turning OFF the rear compartment lamp.

Supplemental Inflatable Restraint (SIR) Lighting

The RIM will provide interior lamp illumination in the event that an air bag has been deployed. Upon deployment of the air bag, the sensing and diagnostic module (SDM) will send a GMLAN serial data message to the RIM. The RIM will activate the interior lamps approximately 15 seconds after the air bag deployment if the ambient light sensor status is dark and the ignition is in the ON position. The interior lamps will remain illuminated until there is a change in the power mode.

Vanity Mirror Lamps

The vanity mirror lamps operate in all ambient light conditions. When the cover on the sunshade is opened, a switch internal to the sun shade closes to provide a direct path to ground. Closing the cover opens the contacts and turns OFF the vanity lamps.

Interior Lamp Dimming

Interior lamp dimming are lamps that may be dimmed by operating the driver information center (DIC)/dimmer switch. This group consist of the following lamps

1. Ashtray lamp
2. Door switches
3. DIC dimmer switch
4. Hazard warning switch
5. Heated seat switches
6. HVAC control head assembly
7. Ignition mode switch
8. Instrument panel cluster (IPC)
9. Memory seat switches
10. Power window switches
11. Radio
12. Rear climate control panel
13. Steering wheel controls
14. Sunroof control switch
15. Traction control switch
16. Transmission shift indicator lamp
17. Trunk release switch

When the park lamp switch is in the ON position, the instrument panel module (IPM) energizes the park lamp relay. With the park lamp relay energized, battery positive voltage is supplied through the DIMMING fuse to the instrument panel lamp fuse supply voltage circuit of the IPM. Upon receiving this voltage supply the IPM requests the status of the ambient light sensor from the climate control panel (CCP). The CCP sends a GMLAN serial data message indicating a Light or Dark status of the ambient light sensor. The IPM will default to dark if the message is not received. If the status of the ambient light sensor is light, then the interior back lighting will not be activated. The IPM also receives an input from the instrument panel (I/P) dimmer switch. The IPM provides the I/P dimmer switch with a 5-volt reference voltage and ground. The I/P dimmer switch is a potentiometer that varies the input signal voltage to the IPM between 0.36-4.23 volts. This input determines the intensity level of the back lighting illumination. The driver may change intensity of the back lighting by positioning the I/P dimmer switch between the minimum and maximum settings. The IPM will default to full intensity if the input from the I/P dimmer switch is not within the specified values. Upon receipt of all the fore mentioned information, the IPM sends a GMLAN serial data message to the CCP, IPC, radio, and all the door modules indicating the ON/OFF status and intensity level of the back lighting. The CCP, IPC, and radio incorporate vacuum fluorescent (VF) lamps that are illuminated at full intensity with the ignition in the ON position. The CCP, IPC, and radio will adjust the VF lamp intensity as requested by the IPM by varying the pulse width modulation of the power feed circuit to the VF lamps. When the door control modules receive the GMLAN serial data message, each door module will supply pulse width modulation (PWM) voltage to the door switch LEDs at the requested intensity. The IPM also supplies voltage to all the remaining lamps at the proper PWM voltage to achieve the requested intensity. The PRNDL incorporates LED lamps that are illuminated at full intensity with the ignition in the ON position. When the park lamps are active, the IPC will adjust the PRNDL LED intensity as requested by the IPM by varying the pulse width modulation of the LED dimming signal circuit to the lamps. All the interior black lighting lamps are permanently grounded.

To provide battery run down protection, the interior lamps will be deactivated automatically under certain conditions. The rear integration module (RIM) initiates a 10-minute timer if the interior lamp relay control output is still active, and the ignition switch is in the OFF position. The RIM timer is set to 3 minutes until the vehicle mileage is above 22.5 km (14 mi). At the end of the designated time, the RIM will deactivate the interior lamp relay, disabling the interior lamps. This feature will be cancelled if any power mode other than OFF becomes active. The RIM will reset the timer if any interior lamp switch is turned ON, a door is opened, or the remote control door lock receiver (RCDLR) module is activated.