Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
Every vehicle's headlights must aim within federal tolerances to ensure visibility and prevent glare for oncoming drivers. The wall method checks aim using masking tape marks at a measured distance from the vehicle. This procedure teaches the test method and how to locate the adjusters; the exact wall distance, beam-cutoff tolerance, and number of turns required for your vehicle are in your owner's manual or from a licensed inspection station.
Necessary equipment
| Item | Note |
|---|---|
| Phillips-head screwdriver | To turn the vertical and horizontal adjustment screws. Your vehicle manual gives the correct size. |
| Masking tape | To mark the wall with reference marks. |
| Measuring tape or ruler | To measure the wall distance and mark the tape positions on the wall. |
| Flat wall or closed garage door material | Place it the specified distance from the vehicle. |
Specifications
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
Prepare the vehicle and testing space
Estimated 9 min to 13 min
- Inflate all tires to the pressure specified on the driver-side door jamb placard.3mReport a problem with step 1, Prepare the vehicle and testing space
- Park on level ground at the wall distance a licensed inspection station recommends.2mReport a problem with step 2, Prepare the vehicle and testing space
- Load the vehicle with the cargo and persons that normally ride in it during typical operation.2mReport a problem with step 3, Prepare the vehicle and testing space
- Rock the vehicle up and down on each corner to settle the suspension, then stop the engine.2mReport a problem with step 4, Prepare the vehicle and testing space
Mark the wall with reference marks
Estimated 6 min to 9 min
- Mark the wall with a vertical line aligned with the center of the vehicle's front bumper.2mReport a problem with step 1, Mark the wall with reference marks
- Mark two more vertical lines on the wall, each aligned with the center of one headlight.2mReport a problem with step 2, Mark the wall with reference marks
- Mark a horizontal line on the wall at the height of the center of both headlights.2mReport a problem with step 3, Mark the wall with reference marks
Position the vehicle and measure beam location
Estimated 2 min
The headlight assembly becomes hot during operation.
Wait five minutes after you stop the headlights before you touch the assembly or the adjustment screws.
- Turn on the vehicle's low-beam headlights and observe where the beam cutoff falls on the wall.1mReport a problem with step 1, Position the vehicle and measure beam location
- Note where the brightest area of each beam meets the wall, and whether it is too high or too low.1mReport a problem with step 2, Position the vehicle and measure beam location
Adjust the headlight alignment
Estimated 20 min to 31 min
- Open the hood and locate the adjustment screws or bolts on the back of the first headlight assembly.2mReport a problem with step 1, Adjust the headlight alignment
- Locate both adjuster screws on the headlight assembly per your owner's manual instructions.2mReport a problem with step 2, Adjust the headlight alignment
- Adjust the vertical screw until the beam cutoff falls the specified amount below the centerline.3mReport a problem with step 3, Adjust the headlight alignment
- Adjust the horizontal screw until the beam cutoff aligns with the headlight's vertical centerline.3mReport a problem with step 4, Adjust the headlight alignment
- Repeat steps 10 through 13 for the second headlight, then stop the headlights.10mReport a problem with step 5, Adjust the headlight alignment
Do a final alignment check
Estimated 8 min
- Start the low beams a second time to do a check that both beam cutoffs meet the markings.1mReport a problem with step 1, Do a final alignment check
- Stop the headlights.1mReport a problem with step 2, Do a final alignment check
- Wait five minutes for the headlight assemblies to cool.5mReport a problem with step 3, Do a final alignment check
- Close the hood.1mReport a problem with step 4, Do a final alignment check
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- headlight beam cutoff
- Also called: no common alternatives
- wall method
- Also called: no common alternatives
- low-beam headlights
- Also called: no common alternatives
- vertical adjuster
- Also called: no common alternatives
- horizontal adjuster
- Also called: no common alternatives
When to use a professional
Stop if the adjustment screws do not turn when you apply reasonable effort with your hand and screwdriver. Stop if the headlight assembly shows cracks or damage. Stop if your vehicle has automatic beam correction that you cannot stop. Stop if you attempt to adjust the aim more than once and it still does not align correctly. Call a professional mechanic for any of these situations.
Common questions
Why does tire pressure affect headlight aim?
Tire pressure changes the vehicle's ride height. Lower pressure makes the vehicle sit lower and angles the headlights downward. The federal safety standard assumes tire pressure matches the manufacturer's specification. Aim measured at incorrect pressure is not valid.
Can I aim my headlights if my vehicle has automatic leveling?
Automatic leveling systems adjust the beam when the vehicle is loaded or on slopes. Check your owner's manual to learn if the system can be turned off for manual aiming. On many vehicles, the system starts again automatically and overrides the manual aiming.
What is the difference between the right and left beam aim?
The low-beam cutoff on most vehicles is asymmetrical by design. The right (passenger-side) beam angles lower and to the right to reduce glare for oncoming traffic. The left (driver-side) beam aims straight. Your owner's manual specifies the pattern for your vehicle.
How often should I check headlight aim?
Check aim after you replace bulbs, after suspension service or collision repair, or every 12 months if your vehicle is loaded heavily. Aim is also important before long-distance night driving.
Related procedures
- How to change a headlight bulb
- How to check your tire pressure and put the right amount of air in your tires
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
Revision history
Current version 2 · updated 2026-08-03 · next review due 2027-08-03
- v2 · 2026-08-03Resolved two dangling source citations. sae-j599-1997 is unresolvable: SAE J599 is paywalled on sae.org (JS-rendered catalog page, no readable abstract or text without purchase); only third-party mirrors were reachable and those are never tier 1. Dropped it from sources and un-verified the two specifications that cited it (wall distance, vertical beam-cutoff), rewriting them and the corresponding steps to defer to a licensed inspection station or the manufacturer rather than publish an unconfirmed number. fmvss-108-2023 resolved: read in full from the GPO's official govinfo.gov CFR annual-edition PDF (49 CFR Ch. V, 10-1-23 Edition); it supports the general federal-aiming-requirement framing but does not itself state a wall-test distance or cutoff tolerance for consumer aiming checks.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.