I've searched and haven't really found this particular problem discussed...

The self adjustment feature on the left headlight on my '05 MCSc is acting up - when I turn on the low beams, the right headlight drops and adjusts properly, the left headlight starts to drop, then just makes a clicking noise like a nylon (or other plastic) gear is stripped.

Just for grins, I popped open the bonnet, turned on the lights and the self adjust routine worked just fine - both headlights lowered and reset to the proper location. While I was under the bonnet, I opened the back of the headlight assembly, pulled off the ignitor and tried to see the mechanical linkage that moves the lights - no luck...

I'm afraid I know the answer (need to replace the headlight assembly), but before I do that, has anyone run into this before and repaired it?

 

It is possible the gear is worn. When you had the bonnet open, you changed the center of gravity on the housing, and that allowed for the mechanism to function properly.

According to http://www.penskeparts.com/, the Xenon headlight housing is sold as a whole unit. Part number for driver's side is 63 12 7 198 739 and runs $559.24. I don't think you have to replace the control unit, but the part number is 63 12 7 176 068 and runs $471.20.

I checked the Marketplace parts section, and all of the Xenon assemblies are sold. Only other option is to check E-Bay or go with an aftermarket kit and replace both.

 

Thanks - That's what I was afraid of - and also my thought about working in the horizontal plane (bonnet up) and not in the vertical plane (against gravity), but I was hoping (wishing is more like it) that there might be an obvious fix I wasn't seeing. I also agree that the control unit is fine - the lamp lights fine, and the controls seem to acting right - it's mechanical...

I'll just keep my eyes open and hopefully find a used one somewhere.

 

If you were able to figure out a way to get the gear out, you might be able to get a duplicate made at a machine shop. They can use the original as a guide.