Tools you will need -
* A dark area with a vertical wall you can drive right up to and about 25-35 feet of level room, measured perpendicular to the wall
* Chalk (for drawing on the wall)
* Cardboard or similar opaque material (to cover lights not being adjusted)
* Tools for adjusting lights
* A tape measure (or similar)
Prep the car –
* Fill the gas tank
* Equalize tire pressure
* Put a normal load in the car (your weight in the driver’s seat + weight for any regular passengers)
Initial positioning of the car –
* Put the car’s nose right up close and perpendicular to the wall
* Rock the car side to side to level the suspension
Mark the wall –
* Line "A" - Vertical, at the center (measured side-to-side) of the car
* Line "B" - Horizontal, at the same height as the vertical centers of the headlights
* Lines "C" - Vertical, at the horizontal centers of each lamp (2 lamps = 2 lines, 3 lamps = 3 lines, etc.)
* Line "D" - Horizontal, parallel to Line "B", 3 inches below "B"
Final positioning of the car –
* Keeping the car perpendicular to the wall, back it up until the lights are 25 feet away from the wall
Aiming the Low Beams –
* Turn on the low beams
* Cover one side (you'll be adjusting the other side)
* Turn the adjusting screws on the uncovered light so that the top edge of the light beam is at Line "D" and the angled cut-off point is centered on the intersection of Lines "C" and "D" (see illustration)
* Move the cover to the side you just adjusted and repeat for the (now) uncovered side
Aiming the High Beams –
* Turn on the High beams
* Cover all but one light (usually one of the center high beam lights on a 4-headlight system)
* On the uncovered light, put the center of the high intensity zone on the intersection of Lines "B" and "C" (using the appropriate Line "C")
* Move the cover and repeat high beam adjustment until all lights are adjusted
This will give you a good initial aim. You should "tweak" it if, after driving for a while, the low beams seem to be too high (or too low). Now comes the balancing act - trying to avoid shining your new (brighter) lights in someone's eyes, but giving yourself the best (highest) light pattern possible. Putting the light pattern horizontal cut off at or below the top of the trunk lid of the sedan on the road in front of you is a good measure. Keep it a little conservative, though, the last thing you want to do is attract the attention of the local law officers.
Notes –
This whole process can take about 30 minutes, make sure the gas tank is full and the engine is running so the battery is not drained. Keep in mind that you found that "dark", probably lonely, place to adjust your lights - it just might be a difficult place to find a jump.
No, you didn't use Line "A". It’s there because it's easy to locate and draw and it gives you some confidence in locating the other vertical lines. To locate the other vertical lines, you can draw line "A" and measure out the distance for each lamp (Lines "C"), after measuring those distances on your car, first. The step of drawing Line "A" can be skipped if you can get the car nose right up to the wall and the lines located that way.
If this is your first time adjusting lights, it might be best to sketch out what you want to do. Spend some time locating the correct screws/hardware, and see how the headlights move when the screws are turned one way then the other.
Adjusting the 2 high/low beam lamps (the outboard pair on a 4-headlight system) usually uses the same screws/hardware for both high and low beams. That is to say, you cannot adjust the high beam without messing up the low beam adjustment. Since the low beam is the more critical of the two, adjust the low beams and allow the high beams to go where they will (they’re usually pretty close). On a 4-headlight system, however, make certain the inboard high beams are adjusted properly.
