Just like any other system in your car, your headlights are a complex system that should be properly tuned and maintained. Everyone knows that all cars need to have functional headlights to drive at night. However it's important to note that for your headlights to do their job well, they have to be calibrated properly. If you've noticed that your car's headlights seem dim while you're driving, you might want to check the aim of your headlights. If your headlights' aim is off, it can drastically decrease nighttime visibility. Proper aim will ensure that you get the maximum visibility possible, but safely (not blinding other drivers). There are several reasons that headlights lose their proper aim; one of the most common culprits is a collision that involves front-end damage, but the can also just lose their aim over time for other reasons (like repeatedly opening and closing the hood over time). While you could have a shop aim your lights for you, it might be just as easy (and cheaper) to do it yourself. Here is the most common procedure for aiming your lights:
Step #1 Materials
For this job, you don't won't need many tools. All that you are going to need is a set of screwdrivers (flat head and Phillips head), a role of masking tape (the blue color is the easiest to see), a flat surface (like a wall) and a rag to clean up.
Step #2 Get the Car in Position
First, park the car just a few feet from the wall. You'll want to be as close as possible to the wall, while still being able to move freely between the car and the wall. Turn on the headlights: the beams should shine on the wall in two distinct spots.
Step #3 Mark the Spot
Take out the masking tape and mark the position of each beam on the wall. It's best to place the tape in a distinct X that crosses as close to the center of the beams as possible. Then, put a long string of tape connecting the center of each X. For cars with headlights that use dual filament bulbs, this is all you're going to need. If you have a car with separate high beams, you're probably going to need to mark the location of both the low and high beam lights. The easiest way to figure out your car's configuration is to switch from low to high beams and see if another beam appears. In that case you'll want to mark those spots too. Once the locations of all your lights are marked, move the car straight back about 30 feet from the wall.
Step #4 Locating the Aiming Screws
The headlights are adjusted up and down and side-by side using aiming screws located on the headlight housing. Pop the hood and take a look. Some cars have aiming screws that are easily accessible, and others' are harder to find. Look around the headlights carefully, the aiming screws generally stick out quite a bit more than the others. If you're having trouble locating the screws, you might want to go to a car parts store or auto shop and have the technician there help you locate them.
Step #5 Aiming the lights
Now it's time to aim the lights. It's actually a pretty easy job. The passenger side headlamp should fall directly on the X. If it's off at all, simply turn the screws left or right until it's in the right place. The driver's side lamp should fall about a 1/4th the distance between the two X's away from the left side (so you're not blinding other drivers). For cars with dual beams, simply repeat the process with high beams.