Hopefully somebody can help me figure this out. I have an '03 SL500 w\ Bi-xenon headlamps. Starting about 4 months ago, my passenger side low beam would occasionally fail to turn on, and I'd get an error to the effect of failure in right low beam. I had the stealership check it out, and they told me it needed a new headlamp control module and wanted almost $2000 for the job..(of course this wasn't covered by the extended warranty either). I did some reading online and with a 10mm socket and a #5 torx wrench pulled the control module in about 5 minutes. Didn't see any obvious problems (didn't expect to) and re-installed it, figured I'd track the part down online. Interestingly, I had no further problems with the headlamp after this, so I blamed the problem on an oxidized connection or some such. Then, about 2 months ago it started again. With some fiddling I found that if the light wasn't working, if I gently tapped the control module a few times then re-started the car the headlamp would work again. Bad connection, right? Well, unfortunately this lasted only a week or so, then the light stopped working entirely. Starting last week, the left headlamp started to act up, but this time cleaning the connection, tapping, etc had no consistant effect, and this weekend it stopped working entirely. My high beams have functioned properly throughout.

The control modules are about $750 each- maddening for a part that is simply a mass-produced circuit board.

So- my question is...Before I toss down $1500 on control modules, are there any other possible causes? According to the fuse chart, the headlamps have an "electronic fuse"- I take it this is a self-resetting circuit breaker? If so, this seems like a candidate for the failure, but I have no info on it's location (it likely is integrated into the controller). Does anyone know of a common failure point in these headlamps?

Any input would be greatly appreciated!

 

The only suggestion I have is to purchase replacement modules from www.parts.comat a considerablediscount to the dealer price.