GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Montana 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Lighting System Description

Halogen Bulbs

Caution: Halogen bulbs contain gas under pressure. Handling a bulb improperly could cause it to shatter into flying glass fragments. To help avoid personal injury:

   • Turn off the lamp switch and allow the bulb to cool before changing the bulb.
   • Leave the lamp switch OFF until the bulb change is complete.
   • Always wear eye protection when changing a halogen bulb.
   • Handle the bulb only by its base. Avoid touching the glass.
   • Keep dirt and moisture off the bulb.
   • Properly dispose of the used bulb.
   • Keep halogen bulbs out of the reach of children.

Exterior Lighting

The exterior lighting system includes the following components:

    • Headlamps
    • Daytime running lamps
    • Fog lamps
    • Sidemarker lamps
    • Front park/turn signal/sidemarker lamps
    • Rear tail/stop/turn signal lamps
    • Backup lamps
    • Stoplamps and High-Mounted Stoplamp (HMSL)
    • License lamps

This system also includes all controls and related hardware required for proper operation of these lamps.

Headlamps

    • The headlamp switch on the instrument panel controls the headlamps. Turn the headlamp switch in order to light both of the headlamps and parking lamps. When the headlamp switch is turned, the following lamps will be lit:
       - Headlamps
       - License lamps
       - Parking lamps
       - Tail lamps
       - Sidemarker lamps
    • The turn signal/headlamp dimmer switch lever on the steering column controls the high-beam headlamp operation. In order to change the headlamp operation from low beam to high beam (or high beam to low beam), pull the turn signal/headlamp dimmer switch lever to the full back position (until the detent is felt) and release. The high-beam indicator (blue) in the instrument cluster will light during the high-beam headlamp operation.
    • The turn signal/headlamp dimmer switch lever can be used to flash-to-pass. In order to flash-to-pass, pull the turn signal/headlamp dimmer switch lever back until both the low-beam and the high-beam headlamps are lit. DO NOT pull the lever past the detent. The low-beam headlamp operation will resume when you release the turn signal/headlamp dimmer switch lever to the original position.

Daytime Running Lamps (DRL) (Domestic)

    • The daytime running lamp (DRL) system consists of the following components which are integral to the DRL module:
       - DRL module
       - DRL sensor
    • The DRL system is designed to automatically operate certain exterior lamps, depending on outside light conditions, whenever the ignition switch is in the RUN position.
    • The DRL system operates in both a DAY or a NIGHT mode. In the DAY mode, the turn signal lamps are lit at full brilliance (non flashing). If the system is in the DAY mode and the turn signal switch is on, the turn signal lamps will flash normally.
        In the NIGHT mode the front park/turn signal/sidemarker lamps and the tail lamps are lit at full brilliance.
    • The signal from the DRL sensor determines the DAY and the NIGHT modes. The DRL sensor is a photodiode element, which reacts to changes in light intensity. The DRL module monitors the signal from the DRL sensor and determines whether the system should operate in the DAY or the NIGHT mode.
    • When the DRL module is in the DAY mode, the DRL module supplies voltage to the turn signal lamps (non flashing). When the DRL module is in the DAY mode and the turn signal switch is on, the DRL module will relay the hazard flasher voltage to the corresponding turn signal lamps and they will flash. At nightfall, as light intensity decreases, the DRL sensor signal changes. In response to this change, the DRL module will change from DAY to NIGHT mode as a switching point is crossed.
    • When NIGHT mode is initiated, the DRL applies voltage to the front park/turn signal/sidemarker lamps and the tail lamps. These lamps operate at full brilliance under these conditions.
    • If the parking brake is applied before the ignition switch is turned from OFF to RUN, the DRL operation is canceled. As long as the brake is engaged, this function allows the driver to start the engine and keep the headlamps or turn signal lamps OFF. The DRL system operation resumes as soon as the parking brake is released. This deactivation feature only functions when the parking brake is applied before the ignition switch is turned to RUN. If the parking brake is applied after the ignition switch is turned to RUN, the DRL system operation will not be affected.
        For DRL system wiring information and electrical diagnosis, Refer to Headlights Schematics .

Daytime Running Lamps (DRL) (Export)

    • The daytime running lamp (DRL) system consists of the following components which are integral to the DRL module:
       - DRL module
       - Engine oil pressure indicator switch
       - 2 DRL relays
       - Headlamp relay
       - Parklamp relay
    • The DRL system is designed to automatically operate the low beam headlamps and the tailamps, whenever the ignition switch is in the RUN position and the engine is running.
    • When the engine is running the engine oil pressure indicator switch sends a signal to the DRL module. The DRL module closes the headlamp relay and the taillamp relay. Voltage is applied through the module to the taillamps and the low beam headlamps.

Fog Lamps

    • The fog lamps are mounted in the front bumper fascia on the Pontiac and the Oldsmobile vehicles.
    • The fog lamps will light whenever the following conditions are met:
       - The fog lamp switch is in the ON position.
       - The headlamp or the parking lamp is ON.
       - The high beam headlamps are OFF.

Rear Fog Lamps (Export)

    • The rear fog lamps are housed in the taillamp.
    • The fog lamps will light whenever the following conditions are met:
       - The rear fog lamp module receives a signal from the rear fog lamp switch.
       - The headlamp or the parking lamp is ON.

Front Park/Turn Signal/Sidemarker Lamps

    • The front park/turn signal/sidemarker lamps are located in a separate capsule next to the headlamp. Turn the parking lamp or the headlamp switch at any time in order to operate the front park/turn signal/sidemarker lamps.
    • When a turn is signaled, the appropriate turn signal lamp flashes in order to signal a turn. The turn signals operate only with the ignition switch in RUN. The turn signals will not operate during hazard flasher operation.

Tail Lamps

    • The rear tail lamp includes the following components:
       - Tail lamps
       - Stoplamps
       - Rear turn signal lamps
    • The tail lamps are lit when the parking lamps or the headlamps are in operation.
    • Indicate a turn with the turn signal/Headlamp dimmer switch in order to flash the rear turn signal lamps with the front turn signal lamps.
    • Depress the brake pedal and close the stoplamp switch in order to light the stoplamps. The stoplamps also light when the hazard lights are in operation.

Backup Lamps

    • The backup lamps are part of the tail lamp.
    • Place the transaxle in reverse in order to light the backup lamps.

Stoplamps and High-Mounted Stoplamp (HMSL)

    • The stoplamps are housed in the taillamp.
    • The high-mounted stoplamps (HMSL) is in the top of the liftgate.
    • Depress the brake pedal and close the stoplamp switch in order to light the stoplamp and HMSL lights.

License Lamps

    • The license lamps are located under the liftgate molding handle for the liftgate latch.
    • Turn the park lamp or the headlamp switch to the ON position in order to light the license lamps.

Interior Lighting

Interior Lamp Override Switch

    • The interior lamp override switch is located in the overhead console switchbank. Press the symbol on the bottom of the rocker switch in order to override the control of the interior lamps. The power will shut off from the following lamps:
       - Reading lamp
       - Instrument panel courtesy lamp
       - Instrument panel compartment lamp
       - Cargo lamp
    • Press the top of the interior lamp override switch in order to turn the power to these lamps back on. This will allow the lamps to stay on when any door is opened.

The instrument panel courtesy lamps light whenever a door is opened and the interior lamp override switch is closed.

The instrument panel compartment lamp lights whenever the instrument panel compartment door is opened.

Dome Lamp

    • Open one of the doors or close the interior lighting switch in order to light the center mounted dome lamp.
    • Place the interior lamp override switch in the OFF position in order to cancel the dome lamp operation.

Lighted Visor Mirror

    • The lighted visor mirror, if equipped, is located next to the vanity visor mirror.
    • Raise the lighted visor mirror cover in order to light the mirror.

Overhead Console Reading Lamps

    • The front overhead console includes the following components:
       - 2 reading lamps
       - Storage compartment
       - Switchbank
    • Press the reading lamp lens in order to turn the reading lamp on or off.

There are 2 side rail reading lamps in the third row headliner, above the outboard seating positions. If your vehicle does not have dual sliding doors, there is also a reading lamp in the second row on the left side.

Cargo Lamp

    • The cargo lamp is located in the rear of the vehicle, above the liftgate opening.
    • The cargo lamp does not have a switch. Open the doors and the liftgate in order to light the cargo lamp. You may also enable the interior lamp override switch.

Exterior and Interior Lighting

Most lighting problems are caused by the following items:

    • Loose connectors
    • Open or shorted wiring
    • Burned-out bulbs
    • Bad switches
    • Inadequate grounds
    • Open fuses

Many of these problems are repaired by replacing a part that requires a special procedure, such as a lens and housing sealed together. For these repairs, follow the instructions normally included in the replacement parts package.

When removing a component that requires special sealing items, such as sealing washers, be sure to reinstall those items when replacing the component. If any body sealing items, such as grommets, are disturbed, be sure to repair them so that the passenger compartment remains properly sealed.

Use the following general guidelines in order to diagnose a lighting system problem:

    • Verify the owner's complaint.
    • Attempt to operate the other systems that are powered through the same fuse.
        If the other systems powered through the same fuse are inoperative, replace the fuse. Refer to Headlights Schematics for fuse applications.
    • Check for aftermarket (non-OEM) equipment.
        If add-on accessories are discovered, disconnect the system in order to make certain that the add-on is not the cause of the problem.
    • Check all connectors and related wiring to the suspect electrical component:
       - Poor mating of connector halves
       - Terminals not fully seated in the connector body (backed out)
       - Dirt or corrosion on the connector terminals.
       - The terminals must be clean and free of any foreign material which could interfere with proper terminal contact.
    • Check related ground eyelets for a clean and tight connection.

If the above general guidelines fail to achieve a satisfactory conclusion, refer to Headlights Schematics for further electrical wiring and diagnostic information.