Headlamp Aiming Screen Method

The headlamp assemblies must be aimed for proper illumination of the road. The headlamp assembly aim should be checked when a new headlamp assembly or headlamp capsule is installed, or if service or repairs in the front end area may have disturbed the headlamp mounting brackets.

Horizontal and vertical aiming of each of the composite headlamps is done by turning adjusting screws which move the headlamp capsule in relation to the headlamp frame. The horizontal adjustment screw (2) is located on the rear middle edge of each of the headlamp assemblies, toward the center of the vehicle. The vertical adjustment screw (1) is located on the rear upper edge of each of the headlamp assemblies, toward the outboard side of the vehicle.

Some state and local authorities have specific requirements for aiming the headlamps. These requirements must be followed.

Choose an appropriate aiming area, then prepare the aiming screen as described in the following.

•	The aiming area should be darkened and large enough to accommodate the vehicle and an additional 7.62 m (25 ft) measured from the face of the headlamp capsule lenses to the front of the screen.

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. Make sure the fuel level is 1/2 full or less.
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 capsule lenses directly over the reference line (9) which has been painted or taped on the floor.
6. Locate the vertical centerline on the aiming screen (5) so that it is in line with the center of the vehicle (8). This can be accomplished by sighting through the center of the rear window and over the hood.

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 centerline of the screen comes into alignment with the two 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 assembly low beam bulb. Adjust the horizontal tape on the aiming screen (1) to match this dimension.
10. Measure the distance between the centerline of the right headlamp assembly low beam bulb and the center of the left headlamp assembly low beam bulb. Position the vertical tapes on the aiming screen (2) this distance to the right and left of the screen centerline (4).

1. Raise the hood.
2. Turn ON the low beam lamps.
3. Inspect the horizontal aim.
4. Adjust the aim using the horizontal adjusting screw, to align the left edge of the high intensity zone with the headlamp low beam bulb vertical centerline (1), within the range of 102 mm (4 in) to the left (4) of the lamp bulb vertical centerline (1), to 102 mm (4 in) to the right (3) of the lamp bulb vertical centerline (1) on the aiming screen.
5. Inspect the vertical aim.
6. Adjust the aim using the vertical adjusting screw, to align the top edge of the high intensity zone to the headlamp low beam bulb horizontal centerline (2), within the range of 51 mm (2 in) above (6) the lamp bulb horizontal centerline (2), to 64 mm (2.5 in) below (5) the lamp bulb horizontal centerline (2) on the aiming screen.
7. Turn OFF the headlamps.
8. Lower the hood.

Headlamp Aiming Mechanical Method

If a headlamp testing machine is used, it should give results equivalent to those obtained using the screen method. It should be in good repair and adjustment, and should be used in accordance with the manufacturer's instructions. The machine using a photoelectric cell or cells to determine aim should also have a visual screen upon which the beam pattern is projected proportional to its appearance and aim on a screen at 7.62 m (25 ft). Such a visual screen should be plainly visible to the operator and should have horizontal and vertical reference lines to permit visual appraisal of the lamp beam.

Horizontal and vertical aiming of each of the composite headlamps is done by turning adjusting screws which move the headlamp capsule in relation to the headlamp frame. The horizontal adjustment screw (2) is located on the rear middle edge of each of the headlamp assemblies, toward the center of the vehicle. The vertical adjustment screw (1) is located on the rear upper edge of each of the headlamp assemblies, toward the outboard side of the vehicle.

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

Tools Required

J 25300-D Headlamp Aimer

1. Raise the hood.

Important: Select aim-adjusting tools carefully since one full turn of an adjusting screw will move the aim approximately 89 mm (3.5 in) when measured at 7.62 m (25 ft).

2. Install the J 25300-D to the headlamp capsule lens.
3. Calibrate the mechanical aimers (conforming to SAE J1602) as follows:

3.1.	Set the master fixture to 0 up/down and 0 right/left.

3.2.	Calibrate the aimers on the master fixture to read 0 up/down and 0 right/left.

4. Inspect the horizontal and vertical aim and adjust as necessary.
5. Lower the hood.