1971 Custom Camper Wiring

[TerryDean]

I bought a 1971 Custom Camper which turned out to be more screwy than expected. I'm still recovering from an ignition harness fire and the wiring diagrams here were extremely helpful. The thing is the "custom" part apparently means "no specific documentation". I have a red wire under the drver side battery tray not mentioned in what looks like some sort of filament fuse? It's a black (melted) wire solidly connected in series with the red wire with both ends attached to the red in a plastic cover not attached to annything. Any ideas what this thing is and what I should put back in there, i.e. a fuse or just a connector? Any help appreciated. I will figure out how to post a picture later.