Possessed starter

[AMSting]

I hate electrical problems.
I will do my best to describe what is going on. Please ask questions if you need any more information or clarification.
For my 1980 Cherokee Chief, 360 engine, mostly stock as far as electrical goes.
My son was using this as a DD for school. One morning he went to start as normal, but the starter continued to run after he released the key (engine did not start on first try which is normal). He turned the key off, but the starter kept running. He turned the key back to the start position and released again thinking something got stuck, but the starter kept running. He again turned the key off, but the starter kept running. He eventually removed the battery cable, but the battery was about dead by that time. The starter stopped when the cable was disconnected.
Charged battery.
Replaced starter motor. Everything worked normally for a couple days. Then one day nothing happened when key was turned to start position. Normal dash lights when key is in on position, but nothing happens when key goes to start position.
Confirmed starter solenoid “start” terminal wire shows voltage when key is in start position.
Replaced starter solenoid. Everything worked normally for a couple days. Then, again, one day nothing happened when key was turned to start position. My son tapped on the starter solenoid and the starter then worked with the key. He had to do this a couple times over a week, but all it took was a tap on the solenoid to get the starter to activate with the key in the start position.
I thought maybe the solenoid did not have a good ground, so was going to add a ground wire to the solenoid mount base on the fender. It took me a couple days to get the time, and before I could do this, tapping on the solenoid stopped working. Still had dash lights when key was in the on position, but no starter when in the start position.
I used a jumper wire to confirm the starter solenoid would work. I jumped directly from the battery to the start terminal on the solenoid. The starter motor turned over.
Last weekend I got a start switch to bypass the key. I ran a wire from the battery to the switch, then the switch to the solenoid. Nothing happened when I pressed the switch. Confirmed the switch worked. Jumping direct from battery to solenoid activated starter motor.
I got a new battery. Nothing happened when using the key. Jumping directly battery to solenoid activated the starter. When the jumper was removed, the starter kept going. This is the first time it happened since the very first time that started all this. I removed the battery cable to get it to stop. When I replaced the cable, the starter activated again.
Right now, the battery is disconnected.
I am at a loss. I know there is a wealth of knowledge here, so please help.

[azwagoneer80]

I've had several aftermarket solenoids either stick on or not work at all. I went through 3 in one shot till I got a good one. The best luck I've had so far is the NAPA ones. I keep a spare in the truck just in case now.

[GreenMachine]

It sounds like a grounding issue/short in the wiring somewhere. Could maybe be shorting out something in the solenoid keeping it from disengaging the starter when the key is released from start to run... I know you said you ran a new grounding wire but from my dealings with jeeps it seems like electrical gremlins are almost always caused by bad grounds. And it could be crappy china solenoids too I suppose.

[Joe Guilbeau]

Negative Battery Cable to block, and another ground cable from block to radiator mounting bolts.

You have to have a good ground on this system, there was a post several weeks ago on this very problem, we all learned a lesson on that one.

Do that first, the second item is that these Starter Solenoid Relays are crap, go to NAPA and buy the most expensive unit that they have.

See my post to view Solenoid interior... in this thread the problem was similar to what you are experiencing, it turned out to be his Ignition Control Module.

http://www.ifsja.org/forums/vb/showthread.php?t=131255

[serehill]

All electrical has to be good but I've seen a lot of these solenoids do this when they go bad. The contacts get pitted & weld together Whack the solenoid & see if it turns lose. Connect the bqattery to see. If it does try to start it if it sticks whack the solenoid if it lets go that's the deal. repace it
WITH A GOOD NAPA ONE.

[Joe Guilbeau]

In my above post I indicated that member dooley had a problem with his 1978 FSJ, your 1980 FSJ has a similar wiring scheme as his.

OK, take a look at the following diagram for your vehicle on OLJEEP's site (Tome Collins).
http://oljeep.com/gw/elec/80/1980_ch...k_8cyl_pg1.jpg

At the top of the page that loads you will see the Battery, follow the Positive Battery Cable to the Solenoid.

You will find a Lt. Blue wire on the Solenoid, follow that to the connector and notice that it continues on to the Ignition Module Assembly.

If there is a problem similar to dooley's where the Ignition Module has a short inside it ( it gets the 12Vdc from the Red wire and transfers it to the Lt. Blue wire when the vehicle ignition key is turned to start).

There is probably a Transistor inside that sends power from the Red Wire to the Lt. Blue wire inside the Module that has failed, and when it turns on/off it stays in that state until the Negative Battery Cable is removed, thus removing power from it.

I would troubleshoot it by unplugging the connector and jumpering the Red to Red and the Lt. Blue to Lt. Blue wires together. Unplug the connector and jumper the Red to Red and the Lt. Blue to Lt. Blue; and repeat the test until the starter run on returns.

When it does run on, keep the Red wire intact, and remove that Lt. Blue wire. By doing this you have removed the 12Vdc signal from the "S" Terminal (Start Terminal) on the Solenoid Relay and removed the voltage on that coil inside and so it will release the contacts.

If the starter stops, then you have diagnosed your problem and the Ignition Module Assembly will have to be replaced.

You have also pitted and abused the contacts inside that Solenoid so much that I would go ahead and spring for a new unit as well.

[amcpsycho2]

I've had this happen to me a number of times over the years.I've been told that the solenoid will stick,especially in a low voltage situation.It seems like it welds the contacts together in the solenoid,tapping on it breaks it loose usually.If the low voltage situation isn't dealt with,it happens again,can also burn off the contact for the start wire connection internally.The first couple of times this happened caused a bit of panic for me,especially if the battery cable ends were fastened to the battery well.
Replacing the solenoid with a good quality one,as previously mentioned,
also making sure that there are good grounds,also previously mentioned. Make certain that battery connections are clean,that your charging system is in good order,and that your battery is fully charged and in good shape too.

[lunchbox1671]

Wouldn't hurt to take a look at your turn-key ignition switch on the column. That could be sticking/shorting as well. It sounds like you tried to bypass that, but I wouldn't rule it out.