I'm trying to resurrect a '94 F-150 with the 4.9 and automatic, and I have hit upon a problem. When I go to start the truck it won't crank. It was 200k miles, so figured what the heck and changed the started. Still won't crank. Jumped the relay on the RH fender, and still nothing. Meanwhile, when the key is turned to the on position there is a loud beeping/buzzer. The horn is inop, so I have no idea if this is an alarm system, but I can only assume so. I see nothing from an aftermarket system, and the beeping/buzzer sound comes from a box hanging just below the dash. It has factory connectors, so I can only presume it is a factory part. Help?!

 

If you jumped relay/starter solenoid from cable to cable and got nothing, look for dirty or bad cables , have battery load tested too and put a socket on the crank shaft and see if you can turn it over by hand. seized motor"??

 

Yes, crossing the 2 big connectors on the fender mount solenoid bypasses everything in the cab so it should have turned, or at least tried to. If the motor isn't seized like revbiker mentioned, then you have a bad wire or connection somewhere between the battery and starter.
Don't forget to look at the ground connection - both ends.

 

Are you sure the engine is not locked. Try to turn the engine manually just to see.

 

I checked, and definitely turns over by hand. Battery is new, so I will check the voltage drop across the cables. They look pretty crusty, so that could be it. I won't have a chance to check until Thursday though.

 

There is a very small wire going to your starter (that's the one that the fender mount solenoid actually uses to engage the starter). Check that it has a good solid connection all the way through. Quite often there's a connector in that wire about 4" away from the starter.
You can also use a screwdriver to jump power from the big connection on the starter to the little one to make sure the starter works.

 

So as an update, checked voltage drops. 12.28 volts at the battery, 11.8 at the relay on the fender, 8 at the starter. Ouch. The motor turns over manually, so time to change out battery cables. Hopefully don't have a bad starter from stock to boot, but I will yank it off and get it bench-checked.

 

Sounds like you're on the right track.