Tools you will need -
Prep the car –
Initial positioning of the car –
Mark the wall –
Final positioning of the car –
Aiming the Low Beams –
Aiming the High Beams –
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.
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.