GMC 10335108 Fog Lamp

These models are equipped with composite headlights with adjustment screws that control up-and-down movement, accessible with a long Philips screwdriver on the back of the headlight housing. Left-and-right movement is not adjustable. Adjusting the headlights can be done in several ways, the simplest of which requires a blank wall 25 feet in front of the vehicle and a level floor. Position masking tape on the wall in reference to the vehicle centerline and the centerlines of both headlights. Measure the height of the headlight reference marks from the ground and position a horizontal tape line on the wall at the same height. It may be easier to position the tape on the wall with the vehicle parked only a few inches away. Adjustment should be made with the vehicle sitting level, the gas tank half-full and no unusually heavy load in the vehicle. Turn on the low beams and adjust the screw to position the high intensity zone two inches below the horizontal line. Have the headlights adjusted by a dealer service department at the earliest opportunity. Some models have optional fog lights that can be aimed just like headlights, with no left-and-right adjustments. Position tape on a wall 25 feet in front of the vehicle, tape a horizontal line on the wall that represents the height of the fog light centers, and another tape line four inches below that line. Using the adjusting screws on the fog lights, adjust the pattern on the wall so that the top of the fog light beam meets the lower line on the wall.