i have a 1988 f150 lariat xlt with the 5.8 v8. i went to get somethin to eat a few days ago, and everything was runnin fine. but when i got back, the next time i tried to start it, the starter stuck, even when the key was taken out of the ignition. i tried everything from changing the solenoid (twice) and the battery, to hittin the starter with a hammer. but right now, the problem i'm having is that even with the ignition switch unplugged from the solenoid, as soon as i go to connect the battery, the starter cranks. i'm not mechanically inclined enough to try to work on the wiring, or even know what i'm lookin at for the most part. so my question is, are there any owners or mechanics out there who might know what is wrong with it, and be able to break down how to fix to a level i can understand?

 

Disconnect the large wire that goes down to the starter from the solenoid.
Connect the battery and see if you have voltage on that terminal. If you do then disconnect the battery and then disconnect the small wires from the solenoid (Trigger Wire/s) then connect to battery again. If you still have voltage at the output terminal then the solenoid is stuck in the energized position.

Get another solenoid and verify with it on the bench that there is no continuity between the two large terminals. Connect only the cable from the battery and check that there is no voltage at the output terminal.

Check for voltage at the trigger wire from the starter switch if the ignition switch is not engaged and you have voltage then you have a short upstream somewhere that you need to locate and fix.