Just purchased a 1997 MB S420 sedan last week. Last night, I used the windshield washer system which also activated the headlamp wipers since the lights were on. Problem: one of the headlight wipers is stuck (opposite its normal resting position) over to the side and will not move; the wiper on the other side is also stuck (opposite its normal resting position0 and it sounds like a motor is running on this side anytime the headlamps are turned on....Any ideas on a fix???

Sounds like your wiper motors are toast. As you know, they only work when you use the windshield washers with the headlamps on. They draw their power directly from the headlamps (at least on my '92 300SE).

Headlamps have to come out to service them, if I remember correctly.

I'd reach up behind the headlamps and pull the wire for the motors until you can resolve the problem. You can tell which wire is which (one's for the headlamp power and goes back towards the car, the other wire is for the wiper motor and goes down to the motor itself, which is bolted to the bottom of the headlamp assembly.

The motor that's running is doing so because it's trying to park the blade, but the gears are probably stripped.

These units are not designed to run constantly like a windshield wiper motor - constant running is sure to burn something up.

I would go thru the drill again, turn on lights, wipers and washers and see if they reset, if not its trouble shoot or disconnect

Here's a very good read on the headlamp wiper system. Read posts by "tower."

http://www.benzworld.org/forums/w140-s-class/1183587-headlight-wiper-stopped-working.html?highlight=ptc+wiper

Brett

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1997 S600 sedan