# New Holland TN75DA Trans issue



## Rodgerm (Aug 28, 2019)

I have a New Holland TN75DA with power shuttle trans. It is going back to the dealer for the 3rd time for the same problem, tractor has only 2000 hours on it and after running it for an hour more or less the trans fails to shuttle to forward or reverse. It will attempt to move then it feels like the hydraulic pressure is released from the clutches. When reset with the hand shuttle or foot clutch it momentarily engages and moves a few inches then nothing, no codes. Let it sit overnight or for several hours and all is normal. Dealer has replaced the ECM, some diode in the harness, some pressure sensors and the seat. $3,000.00 in repairs so far and problem is still the same. I have full shop manual which indicates you need the proper software and interface to program this computer and calibrate it. Unfortunately there is only one dealer anywhere near me, wondering if anyone else has had a similar issue with this trans., there is an item called a dump valve next to the forward and reverse selonides I wonder if that could be the problem? The dealer is attempting to get the Regional Dealer Assistant involved by more then just phone calls but this has been going on for 1 1/2 years !!!! Any experience or thoughts would be appreciated. Rodger


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## Fedup (Feb 25, 2014)

I'm no expert on this transmission, but I have worked on a few. There are hundreds of these units in service, with many going for years with little or no trouble. Then there those like yours. Not knowing your dealership, I can't comment on it, but often small dealerships don't have enough such "problem units" to deal with and don't get to see all the problems. This makes trouble shooting pretty much trial and error, often at your expense. 

Yes there may be a dump valve involved, but it's probably not the problem as most likely it's only doing what the computer tells it to. There are two status switches that are similar to a neutral switch. They sense what gears/ranges are selected so the computer can adjust for load when engaging the shuttle. I've seen at least one case where they were a factor in the clutch not engaging. There are so many possibilities for wiring issues it's nearly impossible to list them all. Yours is a DA model so it's probably a cab tractor? That makes things even more difficult to access for troubleshooting. 

Getting a service authority involved should help. Surprised they haven't done so sooner. That broadens the scope. These people get to hear about such problems from all over, not just your local dealer's area.


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## Rodgerm (Aug 28, 2019)

Fedup, Can't disagree with anything you said and yes it is a cab model. I would have been happy to have the manual shuttle but I wanted a cab model since it is going to end up in Maine but of course you have to have the upgrade trans. It seems harder and harder to get a reliable machine these days and trying to work on it is near impossible without some of the dealer equipment. The dealership is supposedly the oldest Ford dealer in the country but are on the smaller side. It also does seem it is some calibration issue or some sensor since even though they replaced the ECU it does the same thing and I do not thing they have a proper diagnosis. One of the reasons I am reaching out on this forum is in an effort to find someone who experienced the same issue. Thank you for your time. Rodger


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## Fedup (Feb 25, 2014)

Calibration? doubtful. That would mean it moves but engages or shuttles erratically or harshly. That's about all calibration will correct. I'm not sure what's available in the way of software diagnostics for the TN series these days. When they were new there was only a small handheld test box that plugged into a harness connector behind the dash. It was supposedly for calibrating and maybe reading error codes. Not really sure. I've still got one somewhere, but can't say I've ever used it with any satisfactory results. For the bigger tractors they used a laptop with all sorts of diagnostics and programming capabilities. The TN never received any of that to my knowledge which helps explain why it's so hard to figure out.


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## Rodgerm (Aug 28, 2019)

Fedup, It sounds like you spent some time with this trans. From what I have have been able to figure out the test box is known as the CDU (Calibration and Diagnostics Unit) which is used to calibrate new ECMs or reload software & pull codes, the manual claims you have to have one of these for a new ECM installation, which is why I ended up at the dealer to begin with. This tractor also uses that plug behind the dash since it is a Power Shuttle Model which allows it to connect with a laptop having specific software, this system was known as EST (Electronic Service Tool) for additional service of the trans. The kick in the head here is the dealer told me that New Holland had them send these units back!!! Really, if true how did New Holland expect these transmissions to be repaired. When they told me about not having the equipment I asked well how did they calibrate the new ECM since the service manual says you have to have this equipment, they indicated the shop manager is able to do it through experience.... This tractor only has about 2000 hours on it and always kept inside, it only looks a few years old and there are still a lot of these trans out there, maybe it is just me but I expect better from a higher end machine even though it is 15 years old. I keep stuff a long time by taking care of it. My 1949 Farmall Cub starts every time I use it, same with my 1973 Ford 4500 TBL and my 1989 Iseki with an Isuzu diesel has only required a water pump. ( Sorry for the rant ) At this point the dealer has continued to work with me so I am continuing on that path for now. Last go round they were still indicating that they thought it was a calibration issue, sounds like you may be correct. Thanks for listening. Rodger


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## Fedup (Feb 25, 2014)

I sincerely hope they sort it out for you. The TN series had been out of production for a few years already when my "dealership days" ended in 2012. At that point I was unaware of any way to connect a laptop to those tractors. That may have changed since. Also, the current production replacement ECM may use a different process entirely for calibration and testing than did the originals, maybe even a different interface and an adapter harness. That I wouldn't know. Other series at that time could be calibrated without software connections. It was done simply following a certain procedure and using buttons on the dash.

My feeling is your problem is not a calibration issue, but more likely a failed (or slightly out of range) component, something circuit related like a wiring or connector problem. There are a number of overlapping circuits between the clutch pedal switches, status switches, pressure switches, all of which are separate but inter-related in the "eyes" of the controller. If it doesn't "see" a combination it wants it simply won't engage the clutch, and the tractor won't move.


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## Rodgerm (Aug 28, 2019)

I completely agree. I feel it is something electrical: a sensor, wire or wire connection because when it works everything works perfect but when it will not engage that's it. The last three times it failed, after being told it was fixed, I noticed it was after running it for 45 min. to an hour leading me to believe it may be heat related as well. Once I let it sit overnight or for hours it's ready to go, unfortunately that makes for a unreliable tractor. Again thanks for your thoughts and at the least you confirmed what I have been thinking for some time, now it's up to the dealer to pin point the issue hopefully. Rodger


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## Chiefrider007 (Oct 20, 2021)

May be late but having the same problem. Did they or you ever get the issue resolved? What ended up being the culprit? Thanks


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## Fedup (Feb 25, 2014)

Chiefrider007 said:


> May be late but having the same problem. Did they or you ever get the issue resolved? What ended up being the culprit? Thanks


I was hoping there might be a reply here. I too would be interested to learn what resolved the issue.

In your case, just what exactly is "the same problem?"


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## Chiefrider007 (Oct 20, 2021)

Tn75da all hydraulics work, can shift gears and ranges but tractor won't move forward or reverse. Shuttle is not working. Approx 650 hours only thing I've found wrong was 2 fuses were blown. Replaced and did not blow again.


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## Fedup (Feb 25, 2014)

Chiefrider007 said:


> Tn75da all hydraulics work, can shift gears and ranges but tractor won't move forward or reverse. Shuttle is not working. Approx 650 hours only thing I've found wrong was 2 fuses were blown. Replaced and did not blow again.


That doesn't sound like the same problem at all. At least not to me. His tractor would work part of the time(when cold, apparently) and at some point would fail to move until it cooled off again. At first glance, yes, both tractors fail to move, so that can be called the same problem. On the other hand the two situations are likely the result of two totally different issues. 

In your case the total lack of movement in either direction opens up a large number of possibilities. When you say all hydraulics work, I take that to include the steering? Both steering and transmission functions are supplied by the same pump so that side of the equation SHOULD be working, at least to some degree. That leaves the electrical part as the biggest suspect. 

As always, one has to start with error codes. As I recall most versions of that transmission were somewhat lacking in diagnostic aids and procedures to read and evaluate error codes. 

What do you have, if anything, in that regard?


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## Chiefrider007 (Oct 20, 2021)

Did you ever get the problem resolved? As many of these tractors there are out there I would think someone would know exactly what's wrong.


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## An Brown (Aug 15, 2020)

Rodgerm said:


> I have a New Holland TN75DA with power shuttle trans. It is going back to the dealer for the 3rd time for the same problem, tractor has only 2000 hours on it and after running it for an hour more or less the trans fails to shuttle to forward or reverse. It will attempt to move then it feels like the hydraulic pressure is released from the clutches. When reset with the hand shuttle or foot clutch it momentarily engages and moves a few inches then nothing, no codes. Let it sit overnight or for several hours and all is normal. Dealer has replaced the ECM, some diode in the harness, some pressure sensors and the seat. $3,000.00 in repairs so far and problem is still the same. I have full shop manual which indicates you need the proper software and interface to program this computer and calibrate it. Unfortunately there is only one dealer anywhere near me, wondering if anyone else has had a similar issue with this trans., there is an item called a dump valve next to the forward and reverse selonides I wonder if that could be the problem? The dealer is attempting to get the Regional Dealer Assistant involved by more then just phone calls but this has been going on for 1 1/2 years !!!! Any experience or thoughts would be appreciated. Rodger


This Professional Manual covers all repairs, servicing and troubleshooting procedures. It is very detailed and contains hundreds of pages with detailed photos & diagrams. 
*New Holland Tn60da Tn60sa Tn70da Tractors Service Repair Manual*


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## Ridgeranch (6 mo ago)

An Brown said:


> This Professional Manual covers all repairs, servicing and troubleshooting procedures. It is very detailed and contains hundreds of pages with detailed photos & diagrams.
> *New Holland Tn60da Tn60sa Tn70da Tractors Service Repair Manual*


I have a 2004 New Holland TN75D with about 1000 hours. Recently after running my tractor I went out to restart it and the mechanical shuttle shifter would not move out of the neutral position into either forward or reverse even though the tractor would start up. Dealer conversations were fruitless and the cab on the tractor made access limited. 
eventually I tried to peer into rear of the tractor to see if I could see what was below the shuttle shifter. There is a shaft running 90 degrees to the tractor axis from the shifter directly to and through the upper transmission housing. I tapped the right side of the shaft with a dead blow hammer lightly and noticed that the shaft moved about 3/16 inches. I tried the shifter and it has worked perfectly since - roughly10 more total working hours on numerous occasions. I want to emphasize that I have what my owners manual calls the "Transmission with range gear and mechanical shuttle," 16forward and 16 reverse as opposed to the electrical-hydraulic shuttle also referred to as the "Power shuttle." As close as I can figure, the position of the transverse rod going from shuttle linkage to transmission was out of position just enough to jam the proper working of the linkage either under the shuttle lever or in the transmission. Hope this helps someone. Sure would like to know if you got your TN70DA fixed.

Kenny Garrison


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