Headlamp Aiming Procedure

Park the vehicle square with the screen (1).
Park the vehicle with the headlamps directly over the reference line (6).
Ensure that all of the components are in place, if work has been completed on the vehicle.
Ensure that the vehicle is on a level surface.
Stop all of the other work on the vehicle.
Ensure that the vehicle has 1/2 tank of fuel or less.
Close the vehicle doors.
Rock the vehicle sideways.
Align the centerline of the vehicle with the centerline (4) of the aiming screen by completing the following steps:
1. 8.1
  
  Mark the vertical center of the rear and front windows with tape.
2. 8.2
  
  Use these lines as sight lines in order to match the centerline of the vehicle with the screen.
Adjust the vertical tapes (2) on the screen in order to match the vertical centerline of each low beam lamp.
Measure the distance from the centerline of the vehicle to the centerline of a low beam lamp.
Adjust the horizontal tapes (3) on the screen in order to match the horizontal centerline of each low beam lamp.
Measure the height (5) from the floor to the center of a low beam.
Illuminate the low beam lamps.

Fig 1: Identifying Aiming Screen
Courtesy of GENERAL MOTORS CORP.
Observe the left and top edges of the high intensity zone on the screen.
Adjust the headlamps in order to accomplish the following results:
- The top edge of each high intensity zone must be within 50.8 mm (2 in) above to 63.5 mm (2.5 in) below the horizontal centerlines.
- The left edge of each high intensity zone must be within 101.6 mm (4 in) to the left or to the right of the vertical centerlines.