I got a 79 f150. I bought a new starter bout a year ago. So i haven't tried crankin it in several months. I go to try and start it up and as soon as i turn the key the starter becomes stuck and the only way to stop it is take the battery cable off. Now when i put the battery to it its automatically starts tryin to crank. I just replaced the solenoid thinkin that might be the problem and its still doin it. I'm kinda at a fix here and not sure where to go from here???????????

 

Disconnect the wire to the S terminal.

and try the battery cable again.

 

If thats the one on the right i tried that and it doesn't try to crank then. atleast as far as i can remember thats how i tried it? Suppose its the ignition switch??

 

Turn the key to off and try it again .

 

the S terminal your referring to thats the small one on the front right??

 

and this cat is tryin to crank whether the key was in the ignition or not

 

as per the diagram

That means the solenoid/relay is toast or there is power in the wire going to that terminal.

please tell what is disconnected and the key position when you hook the battery cable up.
what happens ?

 

alright i replaced the ignition starter switch anyways. but i can take both wires off the s and i terminals and the thing still turns the motor over. somehow the solenoid is bein bypassed i'm guessin. but i don't understand how or why????

 

What was hooked up ?

+ Battery cable to...what ?

If you simply put the + or Neg battery back on the battery then
The contacts in the solenoid have welded themselves together.

Replace the starter solenoid.

 

what would make it weld together then? i mean it did the same thing with the old one. whats to say its not gonna do it again when i put another one on there??

 

The cheap metal parts inside that join together to close the circuit.

The spark in there would act like a arc welder.

Buy a quality part not something from Asia.

where do you live ?

 

Dennis is correct. If you have the + and - cables connected to the relay lugs and nothing connected to I or S and it turns over, you have a short in the solenoid.

 

north GA. I am gonna take it off and try it on another truck to make sure thats the trouble. i got this solenoid from autozone for bout 10 dollars. i guess you get what you pay for but i'm pretty positive that was the only one they had.

 

Do you have swap meets around that area ?

If not I suggest to contact FTE sponsors that sell NOS parts.
They will more than likely have the quality Motorcraft parts from the 70's .