My 99 expy has some problems after a washing, or a very heavy rain. The turn signals stop working.

Also, the rear window wiper stops working often, not related to the washing btw, it stops working any time it hasn't been run in a couple weeks. The wiper will work again if you go give it a tug, then works fine until it sits a few weeks.

Another intermittant problem I'm having is the left rear vent window won't always work. I haven't figured a pattern to that one yet.

Any ideas on what's the source of all these electrical gremlins? Is there a known batch of bad connectors or something like that out there?

Just looking for a place to start troubleshooting. That's difficult when the problems start and stop on their own.

THANKS