I am hoping someone can help me. I was driving my 1977 f-250 yesterday when it completely died. Nothing is working now power to anything and I have no power to my fuse box! I started out with the battery and it tested good. So I checked the terminals and they where fairly clean but cleaned them up anyway and have also cleaned the ground wire from the battery to the block. I have tested all of my inline fuses up by the starter relay and they all tested good, meaning they all tested good before and after the fuse. Then this is when I am starting to have problems, wish I had a better wiring diagram that showed me what wires go where and if there is any other inline fuses under the dash that could have caused this problem. Does anyone know how the wiring runs? Does the power wire run from the alternator straight to the fuse box or does it go to the ignition first. Am I missing something completely obvious. Please if anyone has any suggestions what to do next would be a big help

 

Could be a fusible link on the wire that feeds the fuse box. This would be a section of fusible link wire under the hood near the starter solenoid, attached to the same terminal as the positive battery cable.

Wiring diagrams can be found here: 1973-1979 Ford Truck Wiring Diagrams & Schematics - FORDification.net - the ones for 76 should be similar to your 77, I think.

 

Thank you, I will look at those schematics. I check all the fusible links under the hood unless I missed on somewhere. I don't see how it could be anything else because it was running great one minute and then the next no power to anything.