Burned out relay?
 

Hey all, have a quick question.. on my 91 300E I've had my windshield washer and rear headrest folding magically stop working, when they were worked just fine last time I used them.

I checked the fuse and it's good, when I push the rear head rest fold down button, I do hear a noise, kind of like a "click" but nothing happens.. I'm thinking maybe a relay? Where should I start?

check around the fuse box to see if a list for relay is there. Not sure though, on my w201 the seat relays are located under the seats. I had a problem with my driver headrest not working, I would hear a click every time I pressed the switch to move it but nothing happened. I ended up teaching the click sound under the driver seat which actually turned out to be the relay (opening or closing) so it was functioning correctly, I ended up having to replace the motor to the headrest.

Thanks for the reply, I checked and there isn't anything marked as far as I could tell :( going to keep sniffing around! It's funny you mention the headrests because I'm going to have to replace those as well...

IF you have aluminum fuses Id sure start by replacing them with copper too.
Thats a very low load relay circuit. Low odds on it failing

As a matter of course, replacing the fuses is not a bad suggestion, but you need to get to the seat release and see if it is getting voltage. Do you have a wiring diagram and/or service CD?