GM Service Manual Online
For 1990-2009 cars only

The headlamp adjusting equipment used must comply with the existing guidelines and the manufacture's operating instructions must be observed.

The vehicle has a visual optical headlamp aiming system. The aim has been preset at the factory and should need no further adjustment

However, If the vehicle is damaged in an accident, the headlamp aim may be affected and adjustment may be necessary.

If oncoming vehicles flash their high beams at you, this may also mean the vertical aim needs to be adjusted.

It is recommended that the vehicle is taken to your dealer for service if the headlamps need to be re-aimed. It is possible however, to re-aim the headlamps as described in the following procedure.

The vehicle should be properly prepared as follows:

    • The vehicle should be placed so the headlamps are 25 ft (7.6 m) from a light colored wall or other flat surface.
    • The vehicle must have all four tires on a perfectly level surface which is level all the way to the wall or other flat surface.
    • The vehicle should be placed so it is perpendicular to the wall or other flat surface.
    • The vehicle should not have any snow, ice or mud on it.
    • The vehicle should be fully assembled and all other work stopped while headlamp aiming is being done.
    • The vehicle should be normally loaded with a full tank of fuel and one person or 160 lbs (75 kg) on the driver seat.
    • Tires should be properly inflated.
    • Remove the round plug from the wheelhouse liner in order to access the adjusting screw on the headlamp assembly after closing the hood.
    • The hood must be in the full CLOSED position as adjustments are being completed.

Headlamp aiming is done with the vehicle low-beam headlamps. The high-beam headlamps will be correctly aimed if the low-beam headlamps are aimed properly.


    Object Number: 1858829  Size: SH
  1. To adjust the vertical aim on the headlamps, close the hood, and complete the following:
  2. Find the aim dots (1) on the lens of the lamp assembly.
  3. Measure the distance from the ground (2) to the aim dot on the lamp with the hood in the closed position. Record the distance.

  4. Object Number: 1721042  Size: SH
  5. At the wall or other flat surface, measure from the ground upward the recorded distance and draw or tape a horizontal line the width of the vehicle.
  6. Caution: Do not cover a headlamp to improve beam cut-off when aiming. Covering a headlamp may cause excessive heat build-up which may cause damage to the headlamp.

  7. Turn on the low-beam headlamps and place a piece of cardboard or equivalent in front of the headlamp not being aimed. This should allow only the beam of light from the headlamp being aimed to be seen on the flat surface.

  8. Object Number: 1766311  Size: SH
  9. Adjust the Left Gradient Line (cut off line) set at - 3.0 inches (1.0%) below H-H (Horizontal Axis) within +/- 2.0 inches measured at 25 feet.
  10. Repeat steps 5 and 6 for the opposite headlamp.
  11. Ensure to re-install the wheelhouse liner plug after completing the headlamp aim.