I have recently (last week) acquired my first Mercedes- a 96 SL600 with 30k. The right low beam will sometimes flash, then go dark and the exterior light warning on the dash illuminates. By switching the lights off then on again, the condition rectifies, although sometimes I have to do this a couple of times. The lights may then operate normally for hours. This car has the xenon HID lights. Any idea what I'm dealing with here?
Thanks.

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MrSandman

Most likely culprit is the ballast. The dealer changed driver's side on my 99 E430 and both HID bulbs. However, I did not experience your problem. My problem was that the driver's side was dimmer than the passenger's side.

Car Nut
99 E430 Sport

Sounds like a bad "combination" switch.

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An acceptable diagnostic routine per Mercedes (and I swear I AM NOT making this up!) is to swap the bulbs side to side and see if the problem remains in the same side (ignition unit, not ballast), or if the problem follows the bulb to the other side of the car, in which case of course you have a bad bulb.
Gilly
ps, don't drop the bulb, extremely high pressure, even when cool, even higher when operating.

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I finally switched the bulbs, as the problem became more frequent. The problem stayed on the passenger side, so not the bulb. The schematic shows something called a "combination switch" but I'm not sure how this relates to the headlamps. Might M.B.DOC be referring to the exterior lamp switch, or is the likely culprit indeed this mysterious combination switch guy? Trying a switch seems a cheaper place to start than replacing an ignition unit. Any other suggested diagnostics?

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MrSandman

The combination switch is the turn signal switch. It's also the highbeam/lowbeam switch and the wiper switch, hence the name combination switch. I'd get the system diagnosed in a shop at this point, you're dealing with high voltages in that xenon system, nothing to play around with, ya could get hurt.
Gilly

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