Vehicle Preparation

Prepare the vehicle for checking the headlamp beam aim as follows:

1. Make sure that all the components are in place on the vehicle, if other service has been performed on the vehicle.
2. The vehicle must have a full tank of gas.
3. Make sure the tires are inflated to the proper pressures.
4. Stop all other operations of work on the vehicle.
5. Position the vehicle so it is square with the aiming screen, and with the headlamp capsules directly over the reference line which has been painted or taped on the floor.
6. Locate the vertical center line on the aiming screen (3) so that it is in line with the center of the vehicle (4). This can be accomplished by sighting through the center of the rear window and over the hood.
   Fig 1: Preparing Aiming Vehicle

   Courtesy of GENERAL MOTORS CORP.

   Mark the vertical center of the front and rear windows with narrow tape. Use these marks as sights to locate the centerline of the vehicle. Move the vehicle or the screen until the center line of the screen comes into alignment with the 2 points.

7. Close the doors.
8. Rock the vehicle sideways to stabilize the suspension.
9. Measure the height from the floor to the horizontal center of a headlamp capsule lens (6). Adjust the horizontal tape on the aiming screen (1) to match this dimension.
10. Measure the distance between the centerline of the right headlamp capsule lens and the center of the left headlamp capsule lens (5). Position the vertical tapes on the aiming screen (2) this distance to the right and left of the screen centerline.