GM Service Manual Online
For 1990-2009 cars only

Aim the headlamps for proper illumination of the road. Inspect the headlamp aim under the following conditions:

    • When a new headlamp, halogen bulb assembly, is installed.
    • If service or repairs to the front end may have disturbed the headlamps or their mountings.

Headlamp focus is set when the unit is made. No adjustment of focus is possible.

Important: Some state and local laws specify requirements for headlamp aim. Ensure that you follow these laws.

Horizontal aim is done with an adjusting screw on the inboard side of the headlamp assembly. Vertical aim is done with an adjusting screw in the upper outboard area. When aiming the headlamps follow the instructions below.

Aim Preparation

In order to prepare the vehicle for aiming the headlamps, perform the following steps:

    • Completely assemble all of the components on the vehicle.
    • Place the vehicle on a level surface.
    • Stop all unnecessary operations or work on the vehicle that affect the vehicle trim.
    • Close the doors.
    • Stabilize the suspension.
    • Ensure that the fuel level is full.
    • Rock the vehicle sideways.
    • Ensure that the tires are inflated to the proper pressure.
    • Ensure that the driver or a similar weight (approximately 165 lbs) is in the vehicle driver seat.

Location

Ensure that the work area is darkened and large enough to allow for the vehicle and an additional 7.62 m (25 ft). The distance for this procedure is measured from the face of the headlamps to the front of the illumination surface. Ensure that the floor upon which the vehicle rests is level with the bottom of the illumination surface. Compensate accordingly if the floor is not level.

Aiming Screen

If you are using a screen, ensure that the following criteria are met:

    • The screen is at least 1.52 m (5 ft) high by 3.66 m (12 ft) wide
    • The screen has a matte white surface and is well shaded from ambient light
    • The screen is in proper adjustment with the floor on which the vehicle rests
    • The screen is movable
    • The screen can be aligned on a parallel with the rear axle of the vehicle

Align the center of the screen with the center point of the two headlamps.

Ensure that the screen provides the following features:

    • A vertical centerline
    • Two laterally adjustable vertical tapes
    • One vertically adjustable horizontal tape

If a regular commercial aiming screen is not available, use a wall with a clear, uninterrupted area at least 1.83 m (6 ft) high by 3.66 m (12 ft) wide. Ensure that the surface is finished with a washable, no-gloss white paint.

After the aiming screen is set up and located, paint or tape a reference line on the floor 7.62 m (25 ft) from the screen. Park the vehicle with the front of the headlamps directly over the reference line.

Visual Procedure

  1. Prepare the vehicle. Refer to Aim Preparation.

  2. Object Number: 276643  Size: SH
  3. Park the vehicle in proper alignment with the screen. Ensure that the headlamps are located directly over the reference line.
  4. Ensure that all the vehicle components are in place if other work has been done on the vehicle.
  5. Use the following procedure in order to line up the centerline of the vehicle with the centerline (2,3) of the aiming screen:
  6. 4.1. Use tape to mark the vertical center of the vehicle on the front and rear windows.
    4.2. Use these lines as "sights" in order to line up the centerline of the vehicle and the screen.
  7. Adjust the vertical tapes on the screen to match the vertical centerline (1) of each lamp. Measure the distance from the centerline of the vehicle to the centerline of a low beam lamp.
  8. Adjust the horizontal tapes on the screen to match the horizontal centerline of the low beam headlamp. Measure the height from the floor to the center of a low beam.

  9. Object Number: 276644  Size: SH
  10. Turn on the low beam lamps. Adjust the headlamps in the following manner:
  11. 7.1. The left edge of the high intensity zone on the screen for the low beams is on the vertical line for each side.
    7.2. The top edge of the high intensity zone on the screen for the low beam is on the horizontal line for each side.

Mechanical Aiming Procedure (Alternate)

Tools Required

J 25300-A Headlamp Aimer and Adapters

  1. Prepare the vehicle. Refer to Aim Preparation
  2. Use the universal aimer on a level floor. Calibrate the universal aimer to compensate for floor slope, if necessary.
  3. Select and assemble the universal adapter that fits the aiming pad pattern on the lens of the headlamp.

  4. Object Number: 276646  Size: SH
  5. Move the adjustment rods to the number that corresponds with the number located on the headlamp lens (1).

  6. Object Number: 276647  Size: MH
  7. Attach the adapters (1). Ensure that you use the correct adapter (1) with the correct side aimer.

  8. Object Number: 276649  Size: MH
  9. Place the aimers (3) with the adapters on their respective sides, making sure all adjustment rods are contacting the aiming pads. Add or remove an extension stud, if necessary.
  10. Aim the headlamps according to the instructions included in the J 25300-A Headlamp Aimer.