There is probably more than one cause for this problem.
First point, dielectric grease is an electrical insulator. Keep that [mod edit] off of any electrical contact/terminal/etc.
I had a similar problem with my MH. Whenever it rained, the wipers would refuse to turn off. My fix was to use zip ties to pull the wiper motor connector up as far as possible out of the way of any water spray. It has been "fixed" for several years now.
I had first tried cleaning the contacts and sealing the connector without any success.
'06 Winnebago Voyage 33', W20, 8.1L