Aiming headlights

Maintenance/Repairs
1

How does one PROPERLY aim headlights? This is not how does one find and turn the screws, but rather what methodology to aim them.

2

Here’s an example from a Lincoln manual.

Headlamp Aiming

  1. The headlamp aiming procedure depends on what type of beam pattern the headlamp is equipped with. Vehicles may come equipped with visual optical left (VOL), visual optical right (VOR) or SAE only (includes sealed beam type) headlamps. To identify the headlamp beam pattern, look on the headlamp lens. Molded in small letters on the headlamp lens is 1 of the following:
    * SAE
    * VOL and SAE
    * VOR and SAE

  2. Once the headlamp beam pattern is identified, aim the headlamps using 1 of the following methods as applicable.
    * Photometric aimers can aim VOL-, VOR- and SAE-type headlamps only. This is the preferred method of headlamp aiming.
    * Visual or screen method aiming can be used to aim VOL-, VOR- and SAE-type headlamps only.
    * Mechanical aimers cannot be used with VOR- or VOL-type headlamps. Aerodynamic lamps that can be aimed mechanically have 3 nibs molded into the lens of the lamp.

Photometric Aiming

  1. For the photometric aiming procedure, refer to the appropriate photometric headlamp aimer instruction manual.

Screen Method Aiming

All headlamp types

NOTE: Horizontal aim is not necessary for VOL or VOR headlamps.

NOTE: Consult your state vehicle inspection manual for recommended tolerance ranges for visual aiming.

NOTE: The sight shield may need to be positioned or removed for access to the adjusters.

  1. Before starting headlamp adjustment:
    * check the tire inflation.
    * check that no other load is in the vehicle other than a half tank of fuel.
    * check that the headlamps are clean.
    * check for correct headlamp operation.
    * check that the vehicle is on level ground.
    * if the vehicle is equipped with air suspension, make sure that the switch is on.

  NOTE: The vertical wall or screen must be a minimum of 2.4-m (8-ft) wide.
  Park the vehicle on a level surface approximately 7.6-m (25-ft) from the vertical wall or screen directly in front of it. 

  NOTE: The center of the lamp is marked either on the lens (circle, crosshair or other mark) or on the bulb shield internal to the lamp (crosshair or other mark).
  Mark a horizontal reference line on the vertical wall or screen.
     1. Measure the center of the headlamp height to ground and record the measurement. 
     2. Make a 2.4-meter (8-ft) horizontal mark (using masking tape) on the vertical wall or screen at the same distance from the ground as previously recorded. 

  NOTE: This procedure should be done in a dark environment to effectively see the headlamp beam pattern.
  Turn on the low beam headlamps to illuminate the wall or screen and open the hood. 

  NOTE: For SAE-type headlamps, the appearance of the beam pattern may vary between vehicles.
  On the wall or screen, locate the high intensity area of the beam pattern. Place the top edge of the high intensity zone even with the horizontal reference line.

SAE-type headlamps

  1. In addition to the horizontal line marked in Step 3, a pair of vertical lines must be marked at the center line of the headlamps on the wall or screen.

    1. Mark the center line of the vehicle on the wall or screen.
    2. Measure from the center of the headlamp to the center line of the vehicle.
    3. Make two 1.5-meter (5-ft) vertical marks (using masking tape) on the wall or screen at the same distance from the vehicle center line as previously recorded.

  2. On the wall or screen, locate the high intensity area of the beam pattern. Place the left edge of the high intensity zone even with the vertical line corresponding to the headlamp being adjusted.

VOR-type headlamps

  NOTE: The appearance of the VOR beam pattern may vary between vehicles.
  Identify at the top edge of this high intensity area a distinct horizontal cutoff in the beam pattern. If the top edge of this cutoff is not even with the horizontal reference line, the headlamp beam needs to be adjusted.

VOL-type headlamps

  1. For VOL-type headlamps, there is a distinct cutoff in the left portion of the beam pattern. The edge of this cutoff should be positioned 50.2 mm (2 in) below the horizontal reference line.
    1. Horizontal reference line.
    2. Top edge of the beam pattern.
    3. High intensity zone.

Mechanical Aiming

  1. For the mechanical aiming procedure, refer to the appropriate mechanical headlamp aimer instruction manual.
3

The home mechanic method there is pretty standard for most SAE (not VOL/VOR) headlights.

The simple procedure is to make sure you have a big chunk of wall you can aim at (e.g. garage door/side of house/garage) and a big flat level surface in front of it.

Choose a time around dusk or later when its easy to see the light.

Drive the car’s bumper right up to the wall - gently - to be practically touching it. Put a big plus mark on the wall smack in the center of the beams intensity spot. Back up - perfectly straight - so that the headlights are now about 25ft from the wall.

Adjust so that the intensity spot of the headlight is just at the lower edge of the horizontal part of the plus mark and just to the right of the vertical.

Of course, you can always take it someplace with fancier equipment. I have no idea whether or not the results are any better.

4

It’s been ages since I adjusted my own headlights. Car headlights are now so unique to each model and year the process is very different from car to car.

If you can aim the headlights yourself you need to identify which screw moves the projected light side to side, and another up and down.

Most often one side of the car is OK and once I establish that then I work on the side that is “off”. First, work the up and down and get the off side to match up with the good side height wise. Then, if the side to side is projecting too far the the right or left work that screw until you have it correct. I usually have the car about 15 to 20 ft. from the wall, or garage door it is projecting onto.

I do this after dark and then test drive the car and work high and low beams. If you are satisfied, stick with it. If not, tweek the adjustment again and retest. Have the car set up with your typical load when adjusting. Realize with when you hook up the trailer, or load the trunk the headlights will aim high.

Cigroller’s method looks good too, especially if you have to do the adjusting in daylight.