No doubt moisture could cause this. The switch has an O-ring that’s supposed to keep the contacts clean, but eventually everything leaks.
The green disk is keyed to the back of the lock cylinder and rotates to connect the up and down wires to ground.
FWIW, in my switch the short circuit...
I really fixed it!
My 2000 4Runner started randomly rolling the rear window down by itself. My version of this problem also disabled window up/down from the tailgate key switch, and also disabled the rear wiper, so I couldn't just disconnect the window motor. Not that I was willing to do...
