91 Ranger XLT 4.0 OHV 5spd manual 4x4
This weekend I finally took my ranger into the mountains for some light off roading (It was a very mild trail as i'm new to this and didn't want to take it anywhere too dangerous or remote)

Everything was going perfectly. 4x4 worked amazing (both high and low) no weird noises or feelings and although it was incredibly bumpy (I may upgrade shocks) I was proud of my truck's performance!

That is until about halfway up the mountain. While going over some large rocks I suddenly heard the unmistakable noise of my starter engaging! I was so incredibly confused I didn't know what to do, so I put everything in neutral and turned the truck off. It actually continued for a moment or two and then stopped. I looked at my passenger who shared the same facial expression as I and we waited a moment in silence.
After I settled down I attempted to start the truck again, and the exact same thing happened. Everything was in neutral but after the truck started the starter was still spinning!
I puled the key out of the ignition but this time it didn't stop! I didn't know what to do so I threw it into gear and stalled it, which stopped the starter from spinning. a moment later I saw smoke coming from under my hood. I assume I fried the poor bastard.

At this point my truck will not start. I hear the single relay click when I turn the key but the starter is silent.

After some logical thinking I disconnected my power cable to my starter and wrapped it up to prevent it from contacting. My passenger and I then turned the truck around on the very narrow trail and after a push I was able to pop start it and get it all the way back home.
As of now the relay clicks but the starter will not make any noise at all.

I am slightly unsure as where to start testing for things but I would like to fix this issue completely as it freaked me out and is a major safety concern!
Here's where I'm at and some extra details about my situation. If you have any tips or advice please let me know!

1. I had a previous issue with battery cables being cut/corroded so I completely replaced them about two months ago.(replaced both positive and negative cables) I have driven many miles and many engine cycles without any issues over these months and I AM SURE I connected everything exactly how it was connected before. That being said, I will provide pics of my wiring (in another post) in case there is an error.
2. I recently had my starter replaced (in January) by a local mechanic. It was remanufactured but I cannot give a brand name. Again I have been using it for months with no issues. (I already called and they will provide a new starter motor as it was under warranty) I will include a pic of burnt starter as well.
3. I believe my fender mounted starter relay was replaced by a previous owner. It doesn't look like a Motorcraft product. No other info on that but I will post a pic just in case. I hear it click so I assume it's working but I may replace as a precaution, I read they can weld?
4. My battery is very new and in spectacular condition.
5.I have reason to believe the ignition key cylinder was replaced by a PO as well. The keys are very new and shiny, don't look stock.
6. I have heard an uncalibrated(?) actuator rod in ignition could slip and cause starter to engage? The road I was on was VERY bumpy and it's possible something could have shifted.

My plan as of now it to test voltages/connections on all points of my starter circuit and replace any parts that may cause issues. Like I said my mechanic is going to provide a new starter however I am wondering if I should bite the bullet and go with a Motorcraft starter/relay combo just to be safe (I heard they are supposed to be paired? no idea if that is true.)

If anyone could recommend a good place to start I would appreciate it greatly. Oh and i'm almost positive I had a reman PMGR starter installed by local mechanic. I will provide pics shortly.

 

It would be nice if we knew what year and engine you have.
Guessing you have a manual because you bump started it.

 

oops, I thought it displayed my truck with my name at the top of the post.

1991 Ranger XLT 4x4 4.0 OHV Manual 5spd

 

Burnt starter

Current connections on relay

This is the wiring from batt to relay to starter. The wire gauge sizes may be slightly off, I included them just to give an idea of size.

 

What most likely happened is the two wires on the start motor shorted together on the back of starter or in the loom, pull back that loom a bit, looks discolored

The smaller cylinder on top of the starter motor is a Relay/solenoid
The smaller gauge wire activates this relay/solenoid, which does two things
The solenoid part pushes the starter gear OUT to mesh with Ring gear on flywheel, first
The relay part connects the larger battery cable to the starter motor, so it spins, cranks engine

Its possible the smaller wire shorted to 12volts at the stater relay on the inner fender, maybe relay is failing

Or the "S" post wire on this relay is shorting to 12v, it runs to ignition switch, under steering column

Ignition switch(turn to START) 12v--------------------clutch switch-------------------------------------starter relay "S" post

So the 12v from ignition switch passes thru a clutch switch in the cab, to prevent starter from working unless clutch pedal is pushed down all the way

I assume you pressed the clutch pedal down at some point and the Starter Motor kept on turning, so the short to 12v on that wire would have to be between clutch pedal switch and fender mounted relay, if it existed
So not ignition switch issue

And it is possible the starter motors relay/solenoid broke and closed without the 12volts, new just means "NEVER TESTED" these days

 

Hey Ron, thanks for the tips! I think you may be onto something with the short being after the clutch, if there at all. I was definitely pushing the clutch when the issue started happening and I have noticed a small clicking noise recently when the clutch pedal is pressed. Not anything concrete (nor even related) but I should inspect it all as a precaution.
I am ordering a new relay today and will start by replacing that and the starter. If the issue is still present after that then I will take a look at the clutch safety switch and go from there.
Thanks for the advice!

Oh and I realized I submitted an old picture of my starter, before I swapped the battery cables out.
I will post a picture of my starter as it is now for better context.

 

Starter as it is now

 

Replaced the starter with a brand new unit and so far (after five days) there has not been another instance of the starter engaging. I made sure to tighten the connections really well and leave as much space as possible between each post.
I also ordered a new relay on the off chance it is going bad but things are looking all right so far.

I think Ron was right in assuming the two starter wires shorted together on the back of the starter. I will update this post should anything funny happen, but things seem to be looking alright so far!

 

Good stuff

Thanks for the update

 

Interesting find:

I realized my battery hold down must have fallen out at some point! I bought a replacement and when installing it I had to push the battery to one side to get it aligned.
Well I pushed a little too hard and it rammed into the fender mounted relay , bridging the two positive wires. I immediately heard the relay click and my starter got power!
I imagine that on the bumpy trail this is what happened and what caused my starter to engage! I rearranged the wires so they would not touch if squished and secured the battery with a new hold down.
my anxieties have been relieved.

Just updating the thread should anyone else have a similar problem.

 

Nice work, I would bet money that was the original problem