The head light electronic adjustment does not function, what type of control is used (pnuematic, vacumm or direct), what is the control circuit and where are the control units physically located and how do I get to them?
Rtcasper Clarification Request; It is the electrical adjustment (Thumb wheel Adj on facia panel) that is not functioning not the mechanical adjustment on the head lights (Plastic cross head screw adjust L/R and U/D). The thumb wheel is usually a potentiometre adjusting a control voltage applied to the head light motor. On the Merc I can't see the motor and wonder if vertical head light adjustment is vacumme operated, where the vacumme pump is located or where i can get access to the wire loom to trace it though as I don't see how to get behind the facia. ANy suggestions as to how to get to and proove which bits are working? At the moment the headlights are adjusted to point correctly by the mechanical adjustment but this does not enable me to lower the lamps easily when I put a load in the boot.
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It's best to have your headlights adjusted by a shop that has the equipment to do the job. Head light aiming equipment takes into account how level the car is before adjustments. The cost of a ticket for misaligned headlights is more than getting them aimed properly.
Check where the brightness adjuster is for your instrument panel lighting on your vehicle because there will be one. Sounds from what you have said that this is being moved each time you are turning on and off the headlights because they are totally separate controls.
There should be a little screw to turn to adjust the head light. This will be in the head light assembly itself on top. If you have a manual they tell you in that also - but you should be able to find it any way. Some cars use a screw driver and some use a special type of screw driver you may have to buy.
Is there a Check Engine light on?
Either the Idle Speed Motor isn't working or it has reached its limit of adjustment (for one of several reasons)
The idle speed motor is controlled by the engine computer - looking at sensor inputs to adjust the idle. It is merely a controlled air bleed.
Electrical problem will be: motor - wiring to the motor - computer - or sensor input to computer
Non - Electrical problem: air entering the intake manifold not controlled by throttle body i.e. vacumm leak from damaged hose, gasket or crack in manifold - also you may have the throttle body out of calibration (open too much)
If you need to find a vacumm leak you can use a can of carb cleaner - with engine running - spray lightly around vacumm hoses and gaskets - when the engines rpms pickup it is leaking in that area.
WARNING: Carb Cleaner is Flammable - be careful not to start a fire - and have a fire extinguisher handy just in case.
Please let me know what you find out and if this helps at all.
In the U.S. the type,
adjustments, and illumination factors of all automobile lighting devices
are regulated by the Federal Motor Vehicle Safety Standard 108. The
headlights must function and be adjusted correctly. Your high beams must
disperse their beams straight forward and low beams down and to the
right while safely providing illumination without too much or too little
glare. It is wise to check the headlight adjustment on your Mercedes at
least every year. Doing it yourself will save you time and money. It
will also make driving safer for you and others you may meet on the road
at night. All it takes is time, some basic tools and a little patience.
Other People Are Reading
Remove components if necessary to allow access to the
left/right and up/down adjustment knobs. They are on top of the rear
side of the headlight. The upper knob adjusts the beam to the left and
right. The lower knob controls up/down adjustments.
Park with the passenger side of the car parallel to a solid
fence or wall and about four feet from it. When there is dim light or
darkness, turn on the lights and use your screwdriver to adjust the
up/down knob on the passenger-side headlight until the light beam is
parallel to the ground (you can see the beam of light against the
surface of the wall).
Turn the car so that it faces the wall approximately one car
length away. Adjust the up/down knob on the driver-side headlight until
it is at the same level as the passenger side headlight. Then adjust
both sides until the small groove on top of the beam cutoff is directly
in front of the light.
Reinstall any components that you removed. Close the hood.
Tips & Warnings
This is method is generic for Mercedes models. Some may differ, as there are many models out there.
did you manage to fix this problem as i'm having the same problems. the car had a flat battery so tried jump starting it but no luck, replaced battery but can only get headlights/windscreen wipers/passenger window and hazards to work. car won't start and alot of the interior controls are dead, i've checked fuses (replaced 2)
some of these vehicles have a lever on the back where the bulb is that adjusts the shroud in front of the bulb ,but as so many cars get permantly shipped abroad that they dont do it now so you have to buy dealer only headlights
We would need more information on what vehicle you have. But there are usually two screws that are spring loaded. The one to the side of the headlight is to turn left and right. And the one on the top controls the up and down movement. Thanks for asking!