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MX120 PTO Controller keeps losing configuration?


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We have a customers MX120 that we just cannot keep the PTO working on for any length of time. In the past we could not get it to work until we did the PTO "configuration" routine, and then it would work. This time in the process of testing the system we found that the PTO would not run even with 12 volts jumped directly to the PTO solenoid, so we replaced the solenoid/valve assy. We then configured the PTO controller and it is working now.  We have removed the wiring harness from under the cab, removed the loom, inspected and OHM tested the wiring, and checked all of the connections. We tested the PTO RPM sensor, tested the the hrz output of the alt, tested the 1000/540 switch, tested the seat switch. Basically did all the tests shown in the factory service manual. As I said it is working now, and we are hoping that the new PTO solenoid/valve assy fixed the problem once and for all, but given our past track record with this problem we are sceptical.

Anyone ever ran into anything similar? 

Thanks!

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  • pirlbeck changed the title to MX120 PTO Controller keeps losing configuration?

I would question if it's loosing config. I have seen quite a few times that trans oil is in such a bad condition that it scores the solenoid valve. Once this happens it can not move to full "on" position in allotted time. Once command is given for pto, controller is looking for pto rpm as well as engine rpm. Due to solenoid moving to slow it aborts engagement. I have found this on quite a number of MX series tractors.

Normally able to pull a little history and uncover a brake grind up or transmission rebuild that polluted system and wasn't cleaned properly. 

CaseIH served a bulletin about removing o-ring from speed sensor thinking it was holding sensor too far off gear for a good clean reading. The bulletin suggested using teflon tape for sealing speed sensor. 

What codes if any is it showing?  

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Sorry, I don't have the codes that my helper pulled, but I am pretty sure nothing jumped out like a "smoking gun". After we replaced the PTO solenoid/valve the PTO would not run until he did the configuration/calibration routine and then it worked normally and this is at least the third time it acted similarly. I think we have already removed the o-ring from the PTO sensor, but I will double check. Not sure on the past drivetrain failures issue, as the owner purchased it used. The hy-tran was recently changed and the filter has been changed pretty regularly.  

Thanks for your help!

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I have an MX135 that has a few times over the years randomly had the PTO quit.  Every time it was a lack of contact on one of the connections right at the PTO housing.  I will look and see which one it is again.

And this is maybe a stupid question but is the operator keeping the engine speed up at or above 1000 RPM when the pto is engaged?  I haven’t run into it much but the controller will switch the PTO off if the engine speed falls too far below low idle with the PTO on.

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I did replace a PTO controller on an MX150/170 back when they were new...seems like it was the first one we ever sold IIRC. Did the configuration routine a couple times....seems like about a week later you had to redo it again. The tech support people said to replace it....don't recall ever having any problems with it again after that. That's been well over 20 years ago. You can update the software through your dealer's EST if they still have all the cabling for doing those older controllers.

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Gearclash,

My helper Nate has been working on it and he has went over all of the PTO related wiring and he is generally pretty through.

SDMan,

We did have the controller software updated a year or so ago, that did not seem to change the problem. One thing I have not mentioned is this time the tractor came in on a trailer as it would not move because it would not engage the F/R shuttle clutch. A new reverse solenoid coil repaired that problem. I don't think that should of had a bearing on the PTO problem as the PTO problem has been cropping up for 3 years or so.

The customer came and got the tractor yesterday morning, I told him to engage the PTO to test it when ever he thinks about it to see if it will keep working.

Thanks guys for your help!

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