T25 (RK25) PTO Electrical short

BryceSteiner · Sep 9, 2021

This was the first weekend that I have really used the PTO - couple hours and I was mowing. I stopped for a little bit and then started it up again at which it wouldn't do anything even though the dash light was on. I opened the fuse box and found the 5 amp blown for the PTO. I put another in and it blew immediately - light still on the dash).

I suspect a bad PTO Solenoid. Anyone else have this on a new tractor?

BryceSteiner · Sep 9, 2021

I worked on troubleshooting some more. I believe it might be the PTO solenoid. The fuse was not blown as long as the solenoid was not connected. As soon as I would connect it the fuse would blow. I'm thinking of connecting a battery to it just to test it.

Roadworthy · Sep 10, 2021

You can connect a battery to the solenoid to test it but without a fuse in the circuit you may melt your wires if the solenoid has a dead short. With a five amp fuse in the circuit my expectation would put the normal operating current well below five amps. If we say, for the sake of argument, the normal current is three amps an ohmmeter across the solenoid would read four ohms. If the normal current was two amps a solenoid resistance of six ohms would hold the current there. So, you could probably expect a good solenoid to read about five ohms. Don't forget to allow for the resistance of your ohmmeter leads.

ljjhouser · Sep 10, 2021

Welcome to TBN. Can you tell if the solenoid primary part (the closing coil) seems to prove good as Roadworthy mentioned, (and also not an open circuit showing 0 ohms), then the fuse may protect the higher current part of the solenoid and the solenoid may not be the problem, and something downstream is drawing too much current. Don't know what tractor, but if solenoid is cheap, might replace it. Might also talk with dealer mechanic with your guesses and see what he thinks. But I tend to agree with you, If the fuse protects the pto switch and mag coil circuit, then may be pinched or grounded wire or switch, or bad solenoid. Good luck Larry.

BryceSteiner · Oct 9, 2021

Roadworthy said:
You can connect a battery to the solenoid to test it but without a fuse in the circuit you may melt your wires if the solenoid has a dead short. With a five amp fuse in the circuit my expectation would put the normal operating current well below five amps. If we say, for the sake of argument, the normal current is three amps an ohmmeter across the solenoid would read four ohms. If the normal current was two amps a solenoid resistance of six ohms would hold the current there. So, you could probably expect a good solenoid to read about five ohms. Don't forget to allow for the resistance of your ohmmeter leads.

I'm sorry for the delay!
I just got back to testing it. I found something interesting. I had two bolts missing at the PTO shaft that had the held the cover on. I got new bolts and put them back on (without the cover) and then decided to test the PTO and surprisingly it worked! I stopped it and put a 5 amp fuse in (I had a 5 am breaker in). I turned it on and it worked - for 5 seconds. Then it stopped. I checked the fuse and it had blown.

So I guess it was not the bolts. I thought it might be and I might be good. I took the covers off around the steering column and coulnd't find anything that looked worn, burned, or anything else, for the blue/white stripe wire, and the green/black stripe wire.

I did a little more testing. I think there is a dead short in the PTO solenoid. Here's why: I ran a test light on just the solenoid - it made the light turn on. I then decided to use the ohm meter on it and it only went to .01 to .02 - making me think it is not retracting successfully.

Any thoughts?