Mower PTO Cuts Out Intermitently

[Iplayfarmer]

A friend of mine just dropped off a Cub Cadet LT1045. He asked me if I could help him fix a problem with the PTO. He says that the PTO will intermitently just shut off. If he flips the switch off and on, the PTO comes back on again.

I'm going out right now to see if I can find any obvious problems, but I'm shooting in the dark a little bit here. Electrical gremlins are not my strong point. I want to get the collective brain trust of TBN going to help me out. I'll post any new info that I find.

Thanks in advance.

 

[kebo]

A wiring diagram would be helpful here. Really though, the clutch (I'm assuming it uses a clutch or maybe a solenoid type device to engage the PTO) sounds like it might be balky. Check for 12VDC on the clutch when it is in the failing mode. If you do have 12VDC going to the clutch when it should be engaged (but it's not engaging) then you would almost surely have to suspect a bad clutch. If you don't have 12VDC on the clutch when it should be engaged, then you would need to start tracing back to find where the open circuit is.

If you've ruled out the clutch, I would then suspect a loose connection, which could be caused by corrosion inside a connector, a wire that has been pinched, a loose screw on a ground connection, or any number of things. If you have a wiring diagram, you should be able to trace out the wiring and inspect it closely. Good luck.....

 

[Iplayfarmer]

Thanks for the feedback, Kebo.

I cleaned all the connections and started mowing my lawn with it. Sure enough, after about a round and a half the PTO cut out. I checked the voltage at the last connector before the PTO clutch and I got nothing. I flipped the switch on and off, and I had 15 volts. I'm suspecting a bad switch. The mower is less than a year old. He got it this spring so I don't suspect corrosion of the wiring yet.

 

[kebo]

What I would do is the next time that happens (clutch disengages), see if you can check each contact on the PTO switch (to ground). If it has 12VDC on each contact (assuming it uses two contacts for the circuit), then the switch is most likely ok and the problem lies somewhere else. If the switch has 12VDC on one terminal, and the other one doesn't then you are most likely correct with your assumption that the switch is bad. A wiring diagram will show you what all is involved in that circuit though.

 

[Iplayfarmer]

What I would do is the next time that happens (clutch disengages), see if you can check each contact on the PTO switch (to ground). If it has 12VDC on each contact (assuming it uses two contacts for the circuit), then the switch is most likely ok and the problem lies somewhere else. If the switch has 12VDC on one terminal, and the other one doesn't then you are most likely correct with your assumption that the switch is bad. A wiring diagram will show you what all is involved in that circuit though.

When I checked it I had 12v from one lead to ground, nothing from the other lead to ground, and nothing between the two leads. Like I mentioned before, when I worked the switch, I had 12v between the two leads again. I never did check the second lead to ground after I flipped the switch in and out. I'm still pretty sure it's the switch.

I looked up the part, and it's about $30.

 

[D7E]

I have exactly the same problem with mine , But works fine when you press the safetey button ?
I know of others that have had trouble too and have had the safetey thing changed .

 

[Iplayfarmer]

I have exactly the same problem with mine , But works fine when you press the safetey button ?
I know of others that have had trouble too and have had the safetey thing changed .

Thanks for that heads up. I'll have to look into that. I'm glad I saw your response before I ordered the switch. I'll have to try the safety button thing to see if mine has the same problem.

What's the fix for that? Is it a new safety button?

 

[Treemonkey1000]

Switches can get pitted when making connections to higher currents. Or they can get debris in them. If there are any small openings in the switch body you might try hosing the boogers out of them with WD-40. I use that fairly often to clean out switches. Just don't have it splash you in the eyes. :confused2:

 

[Steelstring]

I had the same problem. Open the hood and look on the right side where the hood meets the instrument panel for a black relay. It should be a Hella 4RD 931 524-02. This is the PTO relay. Its shot and needs replaced. Apparently, the Hella relays are know for being susceptible to vibration damage. I found a guy on the web who was selling a chinese direct replacement of this relay for the Cub Cadet. Can't seem to find the site now, but the relay number is a AR4-012-c11S. I took a gamble on this relay and haven't had a problem for two years since. The Hella relay is on ebay right now for less than $5. I think this will fix your issue.

Greenwich Electronics, Inc. doesn't sound chinese.

 

[Steelstring]

I found the guys site for the replacement relay:

Guzzi Relays

 

[Iplayfarmer]

Steelstring,

I found the location, and I found the relay; but the relay I have is a HFV6 012ZS-TR(555).

I looked up the specs on the one you linked to, and this one fits the same socket. I guess it could be the same problem even if it's not the same part number.

 

[Steelstring]

I'm guessing that Cub Cadet simply sources whatever relay is cheapest at the time of manufacturing, so there may be several different brands of the same relay with different part numbers. Pull the relay off of your tractor and compare the diagram on the side (if it has one) to the one on the website. I bet they are the same. For $5, give it a try.

 

[Steelstring]

Check this website for the wiring diagram for your relay.

Download | Datasheet Archive

It appears to be the same as the Guzzi relay.

 

[Iplayfarmer]

I'm guessing that Cub Cadet simply sources whatever relay is cheapest at the time of manufacturing, so there may be several different brands of the same relay with different part numbers. Pull the relay off of your tractor and compare the diagram on the side (if it has one) to the one on the website. I bet they are the same. For $5, give it a try.

That's what I had figured. I sent the guy an e-mail to get the relay coming. I'm with you. For $5 it will at least answer the question if that's the problem or not. It beats the $30 for the switch.

 

[Steelstring]

Good luck! Let us know how it works out!

 

[Iplayfarmer]

Good luck! Let us know how it works out!

It didn't work. I am VERY impressed with the service and shipping time for that relay. It came today, but when I installed it I got the same problem.

I tried D7E's fix, though; and it worked...

I have exactly the same problem with mine , But works fine when you press the safetey button ?
I know of others that have had trouble too and have had the safetey thing changed .

Any more info about what "safety thing" others have changed? I'm happy to report to the owner that he can use his mower, but I'd like to get the right part and fix it right for him.