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The front parking/turn signal lamps are located in the left and right side composite headlamp housings (GM also calls them headlamp capsules). The parking lamps can be operated any time using the headlamp switch. When a turn is signaled, the appropriate front parking lamp switches to signal a turn. The turn signals operate only with the ignition switch in the RUN position and will not operate during hazard flasher operation.
Look the job over carefully. On some vehicles, the parking and turn signal lamp bulbs can be replaced by simply twisting the socket free and replacing the bulb. On other vehicles, the lamp assembly must be removed.
Fig. 1: This parking lamp/turn signal socket has a locking tab that needs to be depressed to rotate the socket
Fig. 2: Depress the locking tab with your thumb, then rotate the socket to remove
Fig. 3: With the socket free, the bulb can be replaced
Fig. 4: Carefully push in the bulb and turn it counterclockwise to unlock it
The side marker lights are located on the sides of the headlamp assemblies. These lamps will light when the headlamp or parking lights are ON. If the headlamp or parking lamps are OFF when a turn is signaled, the appropriate side marker lamp will flash in unison with the with the front turn signal lamp. If the headlamps or parking lamps are ON when a turn is signaled, the side marker lamp and the front turn signal lamp will flash alternately.
Fig. 5: On some applications, the side marker bulb socket can be accessed through the engine compartment or from underneath
Fig. 6: On this application, the side marker bulb lamp is part of the headlamp assembly
Fig. 7: Twist the socket to unlock it and pull the bulb from the socket
The taillamps, stoplamps and rear turn signals lamps are all incorporated into the rear taillamps. The taillamps are lit whenever the parking lamps or headlamps are in operation. The rear turn signal lamps flash with the front turn signal lamps whenever a turn is indicated with the turn signal/headlamp dimmer switch. The stoplamps light whenever the brake pedal is depressed and the stoplamp switch is closed.
Fig. 8: The trim panel is likely held in place with retainers like this. Back out the screw to release tension on the pin legs and remove the fastener
Fig. 9: The taillamp is retained by plastic wingnuts
Fig. 10: Remove the plastic wing nuts from the taillamp housing
Fig. 11: Remove the taillamp housing from the vehicle to service the light bulbs
The high-mounted stoplamp is in the center of the rear window and lights whenever the brake pedal is depressed and the stoplamp switch is closed. The bulbs are accessed from inside the trunk.
Fig. 12: This Grand Prix had a slotted vent panel covering the high-mounted stoplamp assembly. Squeeze the ends to remove or install
Fig. 13: A quarter-turn removes the socket so the bulb can be serviced
NOTE: Do not apply pressure to the plastic bubble of the vertical aim indicator.
Fig. 1: This Oldsmobile Cutlass may be equipped with sealed beam headlamps
The headlamps used on the majority of vehicles covered by this manual are called "composite lamps". Unlike the glass sealed beam units used on older vehicles, these headlamps are made of special plastic using small halogen gas bulbs. The bulbs are replaceable, but they do require special handling.
CAUTION Halogen bulbs contain a gas under pressure. Handling a bulb improperly could cause it to shatter into flying glass fragments. Always allow the bulb to cool before removal. Always use the following precautions to help avoid personal injury.
Depending on the installation, the low-bean and the high-beam halogen bulbs may actually be removable without removing the entire composite headlamp assembly. Look your application over carefully to see there is enough room behind the headlamp to fit your hand to remove the bulb holder. Since removing the composite headlamp assembly is not difficult, the following procedure assumes that the headlamp is being removed from the vehicle for halogen bulb service.
Fig. 2: This Pontiac headlamp uses screws as retainers
Fig. 3: This Buick headlamp uses U-shaped plastic clips as retainers
Fig. 4: This Chevrolet uses multiple special screw type retainers, although it may be possible to remove the halogen bulbs from behind, without removing the headlamp assembly
Fig. 5: This Oldsmobile headlamp uses multiple screws as retainers
Fig. 6: This Grand Prix uses two screws to retain the headlamp assembly
Fig. 7: With the two screws removed, the headlamp assembly is gently moved outboard (away from the vehicle center) to disengage the plastic tabs on the back of the lamp from their retainer slots in the sheetmetal mounting bracket
Fig. 8: This halogen bulb has a large, knurled plastic ring that retains the socket to the headlamp. Turn this ring to detach it
Fig. 9: Pull out the socket with the halogen bulb from the headlamp
Fig. 10: This type of halogen headlamp socket is turned to release and remove, or engage and install
Fig. 11: After twisting the socket free, pull the bulb and connector rearward, holding the base, NOT the glass
Fig. 12: Holding the bulb by the base, unplug from the connector
Fig. 13: Exploded view of a common headlamp bulb replacement
WARNING Do not touch the glass bulb with your fingers. Oil from your fingers can severely shorted the life of the bulb. If necessary, wipe off any dirt or oil from the bulb with rubbing alcohol before completing installation.