Scary few moments, need advice
 

So I get into my truck, 94 3.0 4x4 270k+, and I start her up. Well f*ck, guess what, starter motor stays cranking. So I scramble to get under the hood and get the battery disconnected. Took me maybe 3-4 to get the battery disconnected because I only had a crappy little crescent wrench on me. So, I reattach the battery and start her up and everything seems normal again. Started and stopped it maybe 8 times just to see if I could recreate the issue, couldn't get the truck to do it again.

what could that have been?

Sticky starter relay/solenoid

+1 ^^^

Yes, starter relay is most likely cause and it will do it again

1994 may still have starter relay on the inner fender, or it could be part of the starter motor

You will look for a Red/blue stripe wire on the fender mounted starter relay, or it may be down on starter motor

Gotta find that wire, that's the wire than comes from the ignition switch, and it has 12volts when key is in START position, so that's what activates the starter motor

If its on the fender mounted relay then replace that relay, take a picture so you know where wires go on the new one, this is the power distribution for the whole truck, so needs to go back together the same way.

If red/blue wire is on the starter motor then replace the whole starter motor, could be relay or solenoid problem in that motor


Its a long shot but not a no shot, the ignition switch got stuck in START position, ignition switch is above brake pedal, the Key just slides it into its 4 positions using a rod
But that shouldn't have reset when battery was unhooked, so back burner

Thanks for the responses, is there anyway to trouble shoot it to figure out what exactly is wrong?

The relay, and starter are both pretty much new, less than 6mos old.

thanks again

For that year and motor there are 2 different styles

Does your truck have this type fender mount relay?
If yes, yours is bad and needs replaced. and like RonD said, take a picture so you can put wires back correctly. Notice the 2 small terminals, 1 marked "S" other marked "I"
If no, replace starter and solenoid
https://cimg8.ibsrv.net/gimg/www.ran...ec1185e9ad.jpg

If you have a fender mounted relay and it is NEW then I would replace it.

New used to mean "we tested it and it works"
New now means "you test it and if it fails we will replace it", although most places don't warranty electrical parts

Find battery Positive cable, the larger one, if it is short and runs to a fender mounted relay then replace that relay
If cable is longer and runs directly to starter motor then it could be starter solenoid issue, on top of starter
There is no test if you have the longer cable

The only way the starter motor can continue to run is if it has FULL battery voltage on the larger Positive cable.

So in your case the "relay/solenoid" that connects the large Positive cable to the Starter Motor got stuck in the Closed position, the 60amps needed can cause the "relay/solenoid" to heat up and lock closed, when you unhook either larger battery cable that cuts off the 60amps and "relay/solenoid" can cool down and OPEN

So follow the larger positive battery cable and replace what ever part it is connected to