1990 Merc 500SL - connection between headlights and washer fluid?

When I turn on the headlights a loud buzzing noise begins and the car proceeds to dump out all of the window washer fluid. Washer fluid otherwise does not leak on its own. The car has wipers on the headlights; but I don’t know how to trigger them as on. We’ve had the car a little over a year and this issue just started recently. Any ideas are appreciated!

I’ve never looking into on eof these assemblages, but if the wiper/washer/headlight is all in one assembly and all connected via a single plug, I’d look first for corrosion at the plug.