1977 F150, 390, 2wd, C6. This truck had sat for about a year. It ran like a beast when I put it away, but the battery must have gone bad during that time. I went to use my 300 amp booster. It was dark, both battery cables were black, and long story short, I fried the battery with reversed cables. (Trust me, nothing you could say to me would be worse that what I called myself afterwards).

So since then, I've replaced the battery, replaced the battery cables and checked the ground, replaced the solenoid, replaced the voltage regulator, and checked all the bus fuses in the cab (they're good)

I can jump the solenoid with a pair of pliers and it turns over strong, but I get no spark, like the ignition key is off. There is no accessory power or direct power, no dome lights no headlights, no radio. I'm kind if out of ideas.

 

Check the fusible links. When they get fried, the truck loses all power. I know there's at least one, a '77 might have more.
Look on the battery side of the starter solenoid, there will be several smaller wires going into the alternator harness. At least one of these will have a "FUSIBLE LINK" flag on it. check to see if it's burned out. Tug on it and see if it stretches, if it does, it's bad. New ones are available from the auto parts store. You'll need to splice it in.

 

Mine popped on my '77, and I had the same no power to the cab. Mine was sitting there idling when it happened, and just shut off.

 

Also, if you do find that it's a blown fusible link, don't be tempted to replace it with a regular piece of wire. That would be a major mistake.
Fusible links are sized by their gauge, not amps like fuses. The flag will have the gauge size on it. The one in the picture above is 16 gauge.

 

Ok, thanks a million for the responses. As soon as we get a nice way to work outside, I'll hunt down all the fusible links I can find. Hopefully that's the issue

 

 

Sorry for the lack of follow through. Since the OP, all my time off was either rain, freezing rain, or snow. Next dry day off I'll dig into it. I'm really hoping there isn't one under the dash. The last owner replaced the entire interior, and it's a bird's nest under there. Will post info when I get it.

 

Would this faded yellow and green one be a fusible link? It the only one I see that's not a harness and looks remotely like the example given.

 

Never mind, found it, its taped into a bundle of other wires going through the firewall, I'm just going to run the new one beside it. Dont feel like untaping 8' of wires. Thanks for the info.