GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Headlights

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REMOVAL & INSTALLATION



Sealed Beam

See Figures 1 through 6

Most vehicles covered by this manual are equipped with 1-piece sealed beam headlamps. The lamps are held in position against an adjuster housing using a retaining ring. On older vehicles a headlight bezel must be removed to access the ring. On newer vehicles (starting around 1990), the grille and bezels became a single piece. On newer vehicles, the retaining ring fasteners should be accessible with the grille in position. If difficulty is encountered however, the grille should be removed to ease access and prevent damage to components.



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Fig. Fig. 1: Exploded view of a common sealed beam headlight mounting (with separate headlight bezel shown)

If some or all of the headlight bulbs being replaced still operate, refer to theheadlight aiming procedurelater in this section to ease checking or adjustment of the headlights after installation.

  1. Disconnect the negative battery cable.
  2.  
  3. If equipped with separate headlight bezels, loosen and remove the retaining screws, then remove the headlight bezel from the front of the vehicle.
  4.  
  5. If equipped with a 1-piece bezel and grille assembly (most 1990 and later vehicles ), determine if grille removal is necessary for access to the retaining ring. If necessary, remove the grille from the vehicle.
  6.  
  7. The headlight bulb retaining ring is only held on to the adjuster housing by retaining screws. Remove the bulb retaining ring screws. These are the screws which hold the thin metal ring which holds the bulb against the adjusting plate. Do not touch the two headlight aiming screws, at the center of the top and side of the retaining ring (these screws will have different heads), or the headlight aim will have to be re-adjusted.
  8.  

One way to identify the retaining ring screws is that they will be threaded through a lip on the outer edge of the retaining ring before threading through the adjusting plate housing. One the other hand, the adjustment screws are first threaded through the adjustment plate and then an adjuster located underneath the housing.

  1. Pull the bulb and ring forward and then separate them. Unplug the electrical connector from the rear of the bulb and remove the bulb from the vehicle.
  2.  

To install:
  1. Plug the new bulb into the electrical connector.
  2.  
  3. Position the retaining ring over the bulb, then install the assembly to the adjusting plate. Secure using the retaining screws.
  4.  
  5. Install and secure the headlight bezel or the bezel grille assembly, as applicable.
  6.  
  7. Connect the negative battery cable and check to verify proper adjustment.
  8.  



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Fig. Fig. 2: Loosen and remove the headlight bezel retaining screws/bolts



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Fig. Fig. 3: Some of screws may require Torx® head drivers



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Fig. Fig. 4: Loosen and remove the retaining ring screws



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Fig. Fig. 5: Don't forget the ring screws located under the light



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Fig. Fig. 6: Pull the lamp forward and disengage the connector

HEADLIGHT AIMING



See Figure 7

The headlights must be properly aimed to provide the best, safest road illumination. The lights should be checked for proper aim and adjusted as necessary. Certain state and local authorities have requirements for headlight aiming; these should be checked before adjustment is made.

Headlight adjustment may be temporarily made using a wall, as described below, or on the rear of another vehicle. When adjusted, the lights should not glare in oncoming car or truck windshields, nor should they illuminate the passenger compartment of vehicles driving in front of you. These adjustments are rough and should always be fine-tuned by a repair shop which is equipped with headlight aiming tools. Improper adjustments may be both dangerous and illegal.



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Fig. Fig. 7: Headlight adjustment screw locations for most sealed beam headlight adjusting plates

For most S/T vehicles, horizontal and vertical aiming of each sealed beam unit is provided by two adjusting screws which move the retaining ring and adjusting plate against the tension of a coil spring. There is no adjustment for focus; this is done during headlight manufacturing.

Because the composite headlight assembly is bolted into position, no adjustment should be necessary or possible. Some applications however may be bolted to an adjuster plate or may be retained used adjusting screws. If so, follow this procedure when adjusting the lights, BUT always have the adjustment checked by a reputable shop.

Before removing the headlight bulb or disturbing the headlamp in any way, note the current settings in order to make adjusting the headlights upon reassembly easier. If the high or low beam setting of the old lamp still works, this can be done using the wall of a garage or a building:

  1. Park the truck on a level surface, with the fuel tank no more than 1 / 2 full and with the vehicle empty of all extra cargo (unless normally carried). The vehicle should be facing a wall which is no less then 6 feet high and 12 feet wide. The front of the vehicle should be about 25 feet from the wall.
  2.  

The truck's fuel tank should be about half full when adjusting the headlights. Tires should be properly inflated, and if a heavy load is normally carried in the bed, it should remain there.

  1. If this is be performed outdoors, it is advisable to wait until dusk in order to properly see the headlight beams on the wall. If done in a garage, darken the area around the wall as much as possible by closing shades or hanging cloth over the windows.
  2.  
  3. Turn the headlights ON and mark the wall at the center of each light's low beam, then switch on the brights and mark the center of each light's high beam. A short length of masking tape which is visible from the front of the truck may be used. Although marking all 4 positions is advisable, marking 1 position from each light should be sufficient.
  4.  
  5. If neither beam on 1 side of the vehicle is working, park another like-sized truck in the exact spot where the truck was and mark the beams using the same side light on that truck. Then switch the trucks so the S/T is back in the original spot. The truck must be parked no closer to or farther away from the wall than the second vehicle.
  6.  
  7. Perform the necessary repairs, but make sure the truck is not moved or is returned to the exact spot from which the lights were marked. Turn the headlights ON and adjust the beams to match the marks on the wall.
  8.  
  9. Have the headlight adjustment checked as soon as possible by a reputable repair shop.
  10.  

 
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