I have an '85 F150 4wd. It's been sitting for over a year, mainly because when I have the money I don't have the time and vice versa, so I charged up the battery, cleaned all of my connections, crank it over a time or two and it fired right up. So I left it sit and idle few a minutes to get everything lubed up and to make it still ran ok. I turned it off, when I went back to crank it up again, I had no power. Nothing coming into the dash or the key switch. What happened? I can't find anything, I've checked everything that I can think of. There's power coming off the battery to the starter solenoid and a few more places but nothing into the cab. Would it be the starter solenoid, the voltage regulator, a blown fuse somewhere, or maybe a Ignition Control Module?

Any and all help would be greatly appreciated!

 

First thing to come to mind are one or more kinda-thick wires connected to same large post on the starter solenoid that has the battery + cable. You should have at least one kinda-heavy wire there that has a fusible link, this is what provides power to the inside of the cab.

I would remove and clean all primary battery connections, including the ground cable at the engine block.

Do the headlights work?

 

Nope, nothing works! no dashlights, no fm, no nothing. I'm about ready to pull my hair out!

 

The headlights are on an entirely different circuit than everything else in the cab, so, once again, I need to ask... do the headlights work?

If they don't, skip what I said above, your problem is at the battery and/or its connections to the vehicle. Check, clean & repair as necessary the primary connections (anything with a fat cable going to it) but here's a question... have you put a voltmeter on the battery and verified it's charged?

 

There's a yellow wire coming off the starter relay. That supplies power to most of the truck. Find the connector in that wire (in the engine bay) and check it. They are known for corroding and not letting power through. I've had to by-pass that connector on a few trucks already.

 

That is exactly what caused the same condition on my "84, one of the pieces inside the connector was corroded away to nothin. Bypassed the connector and all worked. Almost pulled my hair out 'til my buddy brought over his meter and started checking wires. Hot on one side of the connector and nothing on the other.