Headlight wiring troubles

I had a burned brown wire running to my headlight switch, I replaced it and replaced the other wires that it melted to. Everything is set now, the only problem is I have a different brown wire running from a plug on the fuse box that is not hooked up to anything whatsoever. The wire is labeled "F" and is cut off near the connector. I'm hoping that if I figure out where that wire runs to, it might solve my headlight problem. I haven't able to find any diagrams at all.

I've got a 1980 El Camino, maroon metallic, burgundy interior, factory four-speed and a 350 small block. Any tips would be greatly appreciated.