How to Aim a Headlight
A misdirected headlight can not only be a source of irritation to drivers who must look into the glare of one of these lights on an oncoming car or truck, it can also be dangerous. One of these bright lights can temporarily blind a driver in an oncoming vehicle, creating a potentially dangerous situation. To avoid these problems, you can adjust your vehicle's headlights to aim them in a more appropriate direction. Here's how:
Step 1 - Choose a Smooth Vertical Surface as a Reflector
First, you'll need a vertical surface you can project your lights onto. Most any kind of surface will do, but it must be relatively close to the vehicle whose lights you will be adjusting (about 5 feet). The surface you choose must be one that will evenly reflect light from your vehicle's headlamps when they are turned on and reflecting off this surface.
Step 2 - Park Your Vehicle on a Level Surface
Park on a level surface with your vehicle facing the vertical surface you've chosen. A parking surface that is not level will project your vehicles headlamps too high or too low, depending on the slope of the parking surface. If necessary, use a carpenter's level to be sure the parking surface you use is actually level.
Step 3 - Level Your Vehicle
Be sure your vehicle is sitting in a level position. This means, you'll need to be sure your vehicle has no unusual weight in the trunk or truck bed that will change the normal level of your vehicle when it is being driven. If you expect to be driving at night with some type of weight in the back of your vehicle, this same weight should be present in your vehicle when you adjust its headlamps.
Step 4 - Measure Your Headlights
Using a measuring tape, find the distance in inches from the vertical center of your headlights to the surface your vehicle is parked on. Make a note of these measurements. Then, measure the distance in inches from center point of the left headlight to the center point of the right headlight. Make a note of these measurements. Turn on your headlights. On the surface where your vehicle's lights are focused, find the exact center of the light from each headlamp where it reflects on the wall. Make a mark that you'll be able to see when your headlamps are turned off. Mark a second spot 2" below each of those you first marked. Back your vehicle to a distance of 25 feet from the vertical surface. With your headlight shining on the vertical surface, be sure the headlamps are focused halfway between the lower and upper marks you made.
Step 5 - Make Needed Adjustments
If the focus of your headlamps fail to meet the test you performed in the above steps, find the adjustment screws on the rear bracket of each headlamp. You'll most likely need to access these adjustment screws from inside your engine compartment. Make the proper adjustments, so the headlamp lights are focusing on the spots you've marked. You may need a special screwdriver for your vehicle model.