91 300E Headlight wipers inop, Fuse #3 blows

[Rick Hall]

OK, I have looked at the schematic for 2 days now and cannot find what I am looking for so I am asking for help here. I had a problem awhile ago that I want to get fixed now. Passenger side headlight wiper motor is unplugged. When I connect the connector to the bottom of the light, the washer pump runs for about 3 seconds and then fuse #3 blows in the fuse box. Fuse is a white 8A fuse. I have looked at the schematics that are in the back of the MB Chassis manual and cannot find ANY mention of headlight wiper motors. I see where the headlights are wired and how they go through the # 3 fuse but absolutely no mention of a wiper motor. When the connector is left unplugged, everything works fine, headlights,turn signals, parking lights, wipers, washers,etc.
Can anyone help with this? Is the pass side headlight wiper motor out? Is there a relay that has fried? I don't want to throw parts at it.
Any help/suggestions are appreciated.

[outofspec]

Hi Rick,
I had exactly the same problem with my 1990 300 SEL. I purchased the car about 3 months ago and when I got it I noticed the right (passenger side) headlight wiper was unplugged. When I plugged it in I continually and almost immediately blew the fuse. I did some research in the forum archives that said there was some kind of relay integrated into the right headlight motor. Anyway, I had a spare used right headlight wiper motor. I changed it out and it corrected my problem. It has been working perfectly for since then. I can’t tell you why, but I would bet if you replaced that right headlight motor 9with a good one of course) it would take care of the problem.
Hope this helps.
Outofspec

[Rick Hall]

Thanks for the input. I was told that the right side wiper motor was the "main" motor that controlled the system but was confused and concerned that there was absolutely nothing shown on the schematic. I try to learn each time I have to do a repair and prefer to do a proper diagnosis before throwing parts at a problem.
Thanks again for your input. Off to the salvage yard for a new motor.