Coming home last night i turned on the lights on my 1995 SL 500 and tried to work the windshield washer. At that point a very loud sound began emitting from the area around the washer fluid reservoir that only stopped when i turned off the lights. when i pulled over and popped the hood not only was it loud, but hte reservoir area was vibrating.

since it was nighttime, i had no choice but to keep the lights on until i could get home. by the time i had gotten home, the noise had lessened, but it as still there.

weirdest thing i have ever seen - why would turning the lights on and off affect the washer motor/pump or whatever is over in the front left of the car (front right from driver's perspective).

Can anyone tell me what as going on?

thanks
W