My 2001 Ford F150 is having a problem. The truck will start with no problem, but when the key is on off position or even when the key is removed the starter is engaged and cranks the motor. I replaced the ignition switch thinking that was the problem but unfortunately the problem still occurs. Any suggestions as to what the problem is is greatly appreciated!

 

My guess, and it's just a guess, is the relay on the firewall is bad. Some call it a solenoid.

With the key in the off position pull the small wire (it is the one that just slips on) and see if you have any voltage on it. If you do them the problem is probably in the wires for the key. That small wire should only have voltage when the key is turned to the start position.

Good luck.