Headlamp: Adjustments

Tool Required:
J 25300-13 Headlight Aimer

Horizontal and vertical aiming adjustments are made by turning the adjustment screws. The vertical adjustment screw is located at the top center of the headlamp mounting bracket. The aim of the headlamp is raised by turning the vertical adjustment screw clockwise, and lowered by turning the screw counterclockwise. The horizontal adjustment screw is located on the outboard side of the headlamp mounting bracket. Turning the horizontal adjustment screw clockwise moves the aim of the headlamp outboard, and turning the screw counterclockwise moves the aim inboard.

Some state and local authorities have specific requirements for aiming headlamps. These requirements must be followed. Replacement of a headlamp will not normally require an aiming adjustment. However, the alignment should be checked.

Use the headlight aimer, tool J 25300-E or equivalent. Instructions for using the headlight aimer are supplied by the tool manufacturer.
If no special tools are available, the screen method may be used. To use the screen method, it is desirable to have a specific aiming area in a darkened location. The area should be large enough to accommodate the vehicle, plus an additional 7.62 m (25 feet), as measured from the front surface of the headlamp to the surface of the screen. The floor on which the vehicle rests must be level with the bottom of the screen. If the floor is not level, compensate as necessary.

The aiming screen should be at least 1.52 m (5 feet) high by 3.66 m (12 feet) wide with a matte white surface, well shaded from extraneous light, and properly adjusted in relation to the floor. The screen must have a vertical centerline, two laterally adjustable vertical tape lines, and a vertically adjustable horizontal tape line. If a regular commercial aiming screen is not available, the screen may consist of a vertical wall having an uninterrupted area approximately 1.52 m (5 feet) high by 3.66 m (12 feet) wide, finished with a washable flat white paint.

Important
^ For each vehicle checked, the horizontal tape line on the screen must be adjusted. Vehicles of the same model and year will have different heights for the headlamps.
^ Provisions should be made for moving the screen, so that it can be aligned parallel with the rear axle.
^ Once the screen has been set up in a permanent location, a reference line should be painted on the floor to mark the proper location of the headlamps when they are being aimed.

To aim the headlamps using the screen method:
1. Position the vehicle squarely with the screen, so that the front surface of the headlamp is 7.62 m (25 feet) from the aiming screen.
2. Make sure that all vehicle components are properly installed, if other work has been performed on the vehicle. Stop all other work on the vehicle.
3. Make sure the vehicle has 1/3 tank of fuel or less.
4. Close all of the vehicle's doors.
5. flock the vehicle to stabilize the suspension.
6. Align the centerline of the vehicle with the vertical centerline on the screen. This can be done by marking the center of the top edge of the front and rear windows with tape. Use these lines as "sights" to align the vertical centerlines of the vehicle with the screen.
7. Adjust the vertical tape lines on the aiming screen to correspond with the distance between the vehicle's vertical centerline and the vertical centerline of the low beam headlamp.
8. Adjust the height of the horizontal tape line on the aiming screen to match the distance between the floor and the horizontal centerline of the low beam headlamp.
9. Turn on the low beam headlamps and observe the left and top edges of the high intensity zone on the aiming screen.

Adjust
^ The top edge of the high intensity zone must be within 75 mm (3 inches) above to 38 mm (1.5 inches) below the horizontal centerline.
^ The left edge of the high intensity zone must be within 100 mm (4 inches) either side of the vertical centerline.