Elliott, there is a wiring harness connector (4 wires) that connects your START/STOP switch(es) from inside the coach to the generator. That connector is right there either just outside the cover or just inside the cover of the generator. You can easily pull the connector apart and check for signs of water infiltration in the connector itself, such as any white powdery substance, rust stains, maybe even moisture still in there - It's supposed to be weatherproof.... Check for chafed wires on either side of that harness too. A bare wire rubbing against a frame somewhere could be the problem, and of course, when it's wet could exacerbate the problem.
94-Newmar Kountry Star 40-KSDP
Spartan/Cummins 8.3C-300HP/Allison 3060 WTEC-II/25yr RV Tech RVIA Certified/Onan-Cummins Certified