I have an interesting problem on my 1984 Bronco. I had the engine idling the other day after changing the oil and oil sender, and was getting ready to check the timing, when the starter engaged. I shut the truck off, replaced the starter solenoid, and turned the key on, but not all the way to the start position. The starter engaged again at the key's on position, and remained engaged after the engine was running. I left the thing running, and pulled the relay wire off the starter solenoid, and the starter disengaged. I've ruled out the starter, and both solenoids that have been tried on it are good. The schematic seems to indicate that one of the wires from the control module on the distributor might be tied to the relay wire at the solenoid (which has a constant 12V with the key in the "on" position). I replaced the connector going to the control module, which was in pretty bad shape, and the problem still persists. I'm down to either the ignition switch or the control module. Am I on the right track with this? Has anyone ever had this problem?

 

Some of the vehicle's did have this wire. If your solenoid has two small wires going to it, then yes you do have this wire. If these two small wires are on the wrong terminals, then it will give you this problem. It has been mentioned on this forum too, about some replacement solenoids being wire backwards, where the wires will have to be swapped to make it work right.

 

It started this, out of the blue, with a solenoid that had been on there a while. It started yesterday. I changed the connector on the control module today, and the thing worked great the first time I cranked it. I put up the tools, and wanted to check one more time before coming in the house, and it started again. I'm gonna check again tomorrow, but it gives me the feeling that the first cold start will go fine, and it goes down hill from there. Unless something reset when I disconnected the module to replace the connector. I don't know. I'm fishing, I guess. I've never seen one do anything exactly like this.....

 

If you remove the rubber connector from the starter relay & it stops cranking, the ignition switch is shorted out.

 

I'm gonna change that next, and I'll post the results. One more thing, though, that I forgot to mention,,,, The truck will cut off, and the starter will disengage, when you shut the key off. It only does this with the key in the "on" position...

 

The only time the starter relay should get 12 volts from the ignition switch is when the key is at the start position.
Replace the ignition switch and you should be good to go.

 

I second what 87 XLT has to say. Sounds to me the ignition switch needs replaced. Either the rod or the switch has worn/grounded out which is causing the truck to start in the on position.

T. Roberts
UFD Local 1147

 

Ok. Here is the final resolution. I replaced the ignition switch today. The problem persisted. I got a bright idea to hook my meter up to the red/blue relay wire on the front of solenoid, with the wire disconnected from the solenoid. I turned the ignition on, and got 12 volts. While watching the meter, I started squeezing the wiring harness, and shaking, and the sort. Close by the control module that's on the distributor, while checking the harness, the 12v went away. I wiggled again, and it came back. I stripped back the tape and started checking individual wires, and found a huge short on the red/blue wire that appears at the module, and at the solenoid. I fixed all the shorts, reconnected all the harness connections, and the trouble cleared.

 

That pretty much matches the comment in my signature!
AL.

 

Good troubleshooting technique!

 

OOPS, I guess I wont be so quick to blame this sort of thing on the ignition switch in the future. Thanks for the update & congrats on the fix.