Re: Xenon Headlight Adjustment Procedure ??? (archive)

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Posted by Jim Cash on November 02, 1998 at 21:36:46:

In Reply to: Xenon Headlight Adjustment Procedure ??? posted by J Sherman on November 02, 1998 at 18:26:10:

: I could use some help in the proper setup for the Xenon Headlights on my E39, any help would be appreciated.

There are 2 versions of the lights - before April 98 they had leveling bulbs in the lights, after that they have changed. The newer ones don't have the bubble. They still have 2 adjusting knobs, but one does the low beam and the other adjusts the high. There is no longer a horizontal adjustment.

Anyway this is how you can adjust either one.

Car must be on "level" ground and 25 feet from the surface you are shining the lights at.
Gas tank should be toward the full end, and to be perfect you should have the car loaded to a normal load - including someone in the driver's seat.

First - if you have the leveling bubbles you can set them - ignition must be off - turn on parking lights for a few seconds and then turn off. Now set the bubble as a starting point.

Now measure the distance from the centre of the headlight to the ground. At the aiming wall you need to measure up the same distance and draw a mark at that height (note the surface must be perfectly flat between the car and the reflecting wall - otherwise you will have to stretch a level string from the centre of the headlight to the wall to make that mark.

The marks should be dead straight in front of each headlight.

Now draw another mark 2.1" (52mm) down from the other line. That is the aiming line - the point where the light starts to angle up ( __/ ) should be right on this line.

The adjustment range is +/- 1.3" (33mm).

In simple terms - you should get a drop of 2 inches in 25 feet - with no deviation to the left or right.

Now to actually aim the lights.

Turn on the low beam xenons, and wait about 1 minute (they do a calibration run which takes about 30 seconds to complete.)

The use the adjustment knobs to get the cut-off line (boarder line between the light and dark areas) on that aiming line on the wall, as described above. It helps to cover one lamp while you do the other. Both lamps should line up so that you do not get overlapping double shadow lines on the road.

Dat's it Eh !

For interest sake the headlights adjust themselves according to the sensors on the suspension.

They do this periodically about every 30 seconds, or
They do it constantly while you have your foot on the brakes, or when there is significant acceleration or deceleration.


Jim Cash

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