I'm thinking the cables from the solenoid to the starter may be bad.

 

 

Yes. Stuck closed.

 

Deep breath. Slow down. The forum doesn't charge by the word, so it's okay to provide more details. Same for punctuation. I'm old and cranky, and have trouble deciphering single-sentence textese.

Please keep in mind you may have more than one fault going on. Don't keep throwing parts at it in hope of fix.

Let me make sure I understand what has happened so far. Initially, the starter kept running after the key was released from Run to Start. Unfortunately, the truck was driven that way. That starter was toast, no question. You then replaced the starter, but nothing happened. You jumpered across the two big terminals on the starter relay, using a screwdriver, and the new starter worked okay. However, it would not respond to the key.

You then replaced the starter relay. After the first start attempt, it then stuck on and the starter kept running. Is that correct? Or did the starter engage as soon as you reconnected the battery with the new starter relay? This is a big distinction, and very important for troubleshooting.

So the problem seems to have changed with the new starter relay. The original one wouldn't engage (after sticking on that first time), and then the new one wouldn't release. I want to make sure of this distinction, as a change in symptoms is also very important.

With this new relay stuck and powering the starter, what happens when you disconnect the small control wire (red & blue?) on the starter relay? If the relay opens and the starter stops, that means the control circuit (from the ignition switch) is at fault. If pulling the small wire makes no difference, your new starter relay has failed on the first try.


This long-winded post will explain why your original starter relay stuck in the on position. Please note the many references to cheap relays causing problems. You definitely need to use a quality name brand:

https://www.ford-trucks.com/forums/1...i-mean-it.html


Once you get your starter operation back to normal, please add your comments to the thread above to help others, letting us all know what brands did and didn't work.

 

Hey everyone, sorry to wake this thread from beyond but I'm having the same issue: starter stays running after turning the key back to run; matter of fact, the truck fires up as soon as the key hits run...

This is an 85 F250, 7.5l gas, C6 automatic

When I bought the truck, it came with a push button - turn the key to run, push the button and away you go. This system hasn't failed since I bought it so, naturally, I want to mess it all up by going back to turn-key.

-I've verified that the solenoid clicks and disengages
-I've verified that the relays that feed power to the S wire both work
-Battery holds 12+ volts no problem and has been on the trickle charger the whole time
-I've replaced the ignition switch (electrical component)

My concern is that the S wire has a constant 12v when the key is turned to on/run. It's my understanding that the S wire should only see that voltage when the key is turned (and held) to the start position. I tested both the old and new ignition switches and verified that there is no short between the incoming power (heavy guage, yellow wires) and the outgoing (light guage, red and blue wire) unless they key cylinder is turned all the way to start.

I've poured over this thread and I really don't think my issue is covered here...sorry if it is and i missed it - and thanks in advance.

 

You are right the wire going to the S lug should only be hot when the key is turned to start.

Do you have a wire on the I lug?
If so test it for power in run & start.

If no wire then there has to be a short in the harness somewhere.
Dave ----

 

There is a wire on the I lug - should there be power there if the S wire is disconnected? Also, what do you mean by "if no wire then there has to be a short..."

 

Pull the wires off the I lug and test it like you did the wire on the S lug.
Could be wires got swapped and the wire that goes on the I lug would be hot both run & start where the S lug only hot in start.

If you did not have a second wire on the I lug then the S wire has to be getting power from somewhere so thinking short in the harness.
Dave ----

 

There is about .6V on the I wire on run. Switching the two wires results in no crank. Can you verify that the S wire should be getting it's power from those relays (fuel pump relay and a second relay right next to it, I don't know what it goes to)?

Each relay has a pink/black dashed wire that splice into what becomes the S wire at the solenoid

Looks like a factory splice...

S wire terminal

 

This a EFI truck? (not going back to see)
If so then that could be the fuel pump feed when cranking.
IIRC when you first turn the key on the computer sends a signal to the pumps to prim the fuel system.
You then need the pumps running when you are cranking so that splice might be the tie in for that.
Once running the computer then sends a signal to the relays for the pumps to run till turned off.
Just my .02
Dave ----

 

Nah, the truck has a carburetor...

 

No relays in the start circuit. The wire for the start circuit is red with a blue stripe all the way through. It leaves the ignition switch and goes down to the side of the automatic where there is a neutral safety switch. This is where things can go wrong, there is also a circuit at the side of the automatic for the back-up lights, which has power when the key is turned to run. If the wires get mixed up down there, or they get against a exhaust pipe and get melted together, the power for the back-up lights can power the start circuit. Simple way to see where your stray power is coming from is pull some fuses. I would start with the fuse for the back-up lights.

 

Well never mind LOL
My truck is stupid simple also 300 six and a v1 carb LOL
Dave ----

 

So my S and I wires were, indeed, switched; the S wire (red and blue) did, however have a break in it somewhere and it wasn't tripping the solenoid. I ran a new line from the ignition switch to the S post and bingo, bango.

The truck fires up with the key (my original intent) but now I wonder what that I post is supposed to feed and if I need to reconnect it to it's proper destination.