Hi all!
I have an issue that I have been trying to resolve for the past month since I busted it.

I was switching out the battery, and not paying attention I either put the battery in backwards and hooked up the terminals backwards, or I just plain hooked them up backwards. Either way the same result happened. I fried something. It was near the solenoid. Sparks and smoke came out of the general vicinity, I have tried a few things listed below.

A) I purchased a new battery and new post cables and new solenoid to be sure.
B) Purchased and installed new Fusible links, 3 to be exact. 20, 18 and 16 guage
C) Checked the relays, there was corrosion so I cleaned them.
D) Checked all fuses in the cab, all are fine and no corrosion

Now here are my troubleshooting problems.

A) I have NO power past the solenoid. I can cross the Solenoid though it will not turn over. just try to turn over, probably has to do with problem (B)
B) I have NO power in the CAB
C) Battery posts do NOT emit spark when (+) post cable makes contact with post terminal.

I have attached a picture of the Solenoid for you to comment on, I thought had it all figured out with the Fusible Links, though it is still not getting power to the cab.

It is an 1986 F250 4WD the 5.0L

 

The top large terminal in the picture above is the battery terminal correct? And the lower goes to the starter. If that's right, I would poke all those smaller wires going to the large top terminal AFTER those black square pieces to make sure you have power through those. One of those wires should go down in the harness to a splice, which runs to the alternator and also to more fusible links over on the passenger side fender.

You are all around the problem, just keep piercing wires with your testlight or voltmeter till you find were you are losing 12v. I believe the problem is still around the solenoid and the passenger side inner fender.