on my 90sl the #1 fuse powers the anti-theft alarm, the right standing lamp, the right tail lamp, side marker lamp, exterior lamp failure monitoring module, exterior lamp switch, instrument cluster, license plate lamps, and headlight washer. have you tried unplugging the wiper motors one at a time, not the pump, and see what happens? the wiper motor maybe the problem. you'll need to pull headlight to access

 

So far I've tried it with the pump unpluged and the #1 fuse pulled. I didn't think to check lights but I will. It runs fine and no warning lights are on except the fluid level. I had a 1/2 gallon but my reservoir holds 3x that amount. I've purchased more. Not certain where the headlight wiper motor plugs in. I'm sure it is under the reservoir so I will take that out again. HOWEVER if it works like it is and no other lights are out, I may just go with the fuse out and the pump unplugged until it is cooler (November).

 

remove headlights to access wiper motors