New Holland TN70d transmission problems

[Deere9986]

It's been a while since I've posted and it's always been in the deere forum so these NH are new to me. I have a friend whose NH 70D quit moving, he took it to a Kubota dealer since they used to be a Nh dealer also to get fixed. They replaced the shuttle lever and the shuttle valves and it still didn't move. He then had it brought to my place for me to work on (for free of course). They unloaded it off the roll back and it wouldn't start, so i put a battery off my farm tractor on it and it still wouldn't turn over. I got my brother to get in the cab and push the clutch in and put the gears in neutral and i shorted out the starter and got it started. I then got in the cab and tried all the gears and could only get it to creep in reverse in low gear. It would keep going no matter if you pushed the clutch in or not. Got it pulled in the shop and diassembled the dash area looking for wire problems, didn't find any, checked the seat, jumped the wires and still nothing. Tried to shut it off and it stayed running, finally pulled the a fuse to get it to shut off.
I'm going to pull the left tire off tomorrow to check the connections at the solenoids but was curious if i need to be looking elsewhere. I think this tractor has electrical issues because the mfwd will not disengage and his door glass on both sides have been broken for a while.
Could the ecu be out or could it have lost its cal?
I am pretty good on my Deere tractors when it comes to electrical issues but this one has me stumped.

 

[mojoinco]

REad through the threads here for the TN series (55/60/65/79/75). There is also a vineyard line that is the same for the kinds of problem you are having. There are a number of sensors and a computer for the clutch and drivetrain engagement. The switches are not simply open or closed, but have specific resistances depending on which position they are in. On top of that, the computer can take a 'set' that has to be cleared with software.

All is not necessarily lost. There are codes that should be flashing on the console. You will find write ups on how to read them by searching the forum for the TN series (the larger TN series are a different tractor, though some things are similar in operation). There is also a clone model line in the Case-IH line.

You probably saw that the clutch pedal is really just a big spring and a couple of potentiometers. There is an alignment for them and a reset from software that is required. I suspect you have a sensor or two that has taken a hit.

The non-cab models have had issues with corrosion in the dash area. Since this tractor has broken doors, I would take a look at all the connectors you can and confirm no corrosion. I also wonder how well taken care of it is (course it might be stored in a barn or under a roof).

 

[PILOON]

Friend has a couple of TN's.
More than once the problem was a simple module, naturally which one and where is it.
The TN's are not 'vice grips and bailing wire' maintainable units.
Also lots of safety switches that like to attract corrosion.
I gather most TN owners by now know how to bypass most of them.

 

[Harry in Ky]

Start with the obvious, I guess. Look for error code(s). Should be an amber light somewhere on the instrument cluster that will flash to indicate any error codes. I think it's the one with an icon that looks like an open book. It will flash like four times to get your attention, then pause for two seconds and flash again. Pause for two seconds then flash a third time. The second series of flashes indicate the first digit of the code, the third series indicates the second digit. Then it will pause again, longer this time, then repeat. It may read multiple codes, the most critical first, then repeat the process again. The codes will tell you where to look first.

 

[chipdog4]

Dad had this problem on his TN70, no forward only reverse.
I'll have to talk to him to see what exactly it was, but the dealer fixed it for $1,000.
I think it was a control module...