1986 Ford F-150 charging problem

Not sure what type of short I tested it with a test light between the ground wire and neg teerminal between batt.

I thought sbout that but now the alt isn't even hooked up so now I dont know where to go from there any ideas before I go chasing all those wires around thank you for your time

Where do I hook up this jumper wire and also the fuse thing I was under the impression that if I pulled the fuses that the test light would go out on the faulty circuit this was not the case. I also hooked my digital multimeter betweem neg post and ground wire with it set to volts it reads just over 12 volts and this also doesn't change as I pull fuses so thinking problem lies before fuse box also do you have any way what the yellow wire from solinoid to computer does with this wire unhooked mt truck cranks and all lights work but it wont start with it unhooked. There is also a wire from solonid into alt, harness that when hooked up sets my test light off. That wire when disconnected shuts off all power to truck any chance that the two could be on same circut and if so which circut could that be. I cant read wieing diagrams very well and cant figure out which wire does what thank you.