I found a disconnected wire coming through the firewall, routed to somewhere near the battery. It is a single black wire with a yellow rubber end crimped to a "C" screw ring.

I'm having starting problems. It's doubtful this has anything to do with it but I'm checking everything.

 

go on the other side of the firewall and see if you cant trace it down, there is always the chance that somebody did a hillrod attempt at an amplifier install and just left the wire. its not the typical color for amp wire nor does it have a fuse but ive seen people cut the end off of extension cords and use them for power wire, so its true what they say about it taking all kinds.