Some RVs are "slapped together" as cheaply as possible. Even the top dogs develop corossion at terminals and connections. Most likely connections everywhere need some dielectric grease or compound applied after cleaning and securing tightly together. some don't fit together too well either.
Many sit out, in the weather, all the time, from when they are driven off the lot until traded or whatever. Moisture gets into everything when you have lots, of it, around and hot to cold and the other way around. Doesn't even have to be much moisture around for colder metal to draw moisture.
I would check every connector, at the fuse and breaker boxes, and the other ends. Lots of them so it wouldn't be quick. Then there is under the hood or the dash and the connectors and wiring in the roof to lights etc. Any bare wire will corrode too.
