'86 full-size Bronco, 305. When I turn the key to START, the starter will continue to crank even if I put the key back to the OFF position. If I pound on the fender outside of the starter relay a few times with my fist, it will stop. I have replaced the starter relay twice; once with aftermarket from Autozone and once with Motorcraft. No difference. If I pull the slip-on connector on the wire from the ignition switch off of the small terminal post on the relay while the starter is cranking, there is no effect. Starter keeps cranking. If I pull this connector off of the relay first and then jump the positive terminal of the battery directly to the small terminal post on the relay (bypassing the ignition switch), the starter cranks and then CONTINUES TO CRANK after I remove the jumper! Also, there is a small cylinder (looks like a small condenser) mounted next to the starter relay. It has one wire coming out of it that the terminal eye has broken off of. It looks like it used to go to the battery side of the starter relay, but I can't find this device on the factory wiring diagram. Does anyone know where this wire is supposed to go and if this may have anything to do with why the starter keeps cranking? This is driving me crazy!!! What is going on??

 

I believe the small cylinder(it is a condensor or capacitor) probably goes to the positive side of the starter relay, or the yellow wire going to the regulator(which is basically the same thing). It's just for radio noise, and is not important as far as the overall operation of the truck.

As far as your solenoid problems, the solenoid is welding itself together. The first thing I would have recommended is getting a higher quality relay, but you already did that. There is one thing that comes to mind that happened awhile back to another poster.

He kept having the same problems with multiple solenoids, and accidently found out he was inadvertantly causing the problem by putting too much force on the large studs with a wrench. The whole stud was apparently moving in the solenoid body, causing some sort of mis-alignment inside. I believe by putting torque on the stud the opposite direction without loosening the nut, he was able to make the problem go away.

This is the only solution I have to offer.

 

Thanks for the input. I don't think I put too much torque on the screws when installing. Also, I forgot to mention that the starter cranks strongly, not weakly. Not sure if this means anything.

 

From your excellent description of what's going on, the solenoid contacts are definitely welding themselves together. We have had several posts on this in the past year, and it seems there are a large number of inferior quality solenoids being sold. Sometimes someone will change the solenoid only to find out the real problem was somewhere else. In the meantime they have suddenly this new problem of the relay sticking, so the solution sometimes is to put the old one back in.

Like I said, most of the time buying a different brand will fix it too. You bought a name brand though, so I do not know if buying another different brand will work or not.