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Lakeville, MN | I was in the yard working on calibrating the new auto pilot system I installed and all was working normally. I pushed in the clutch to stop and make an adjustment to the auto pilot system and then when I went to take off it would not engage in forward or reverse. The power-shift display shows N, F1, R1 all like normal but it will not move and I do not get a fault code displayed. The tractor came with a operators manual for the Twin Disc transmission it has a few trouble shooting and diagnostic parts. This is what I have checked so far.
8 shift and 1 lube solenoids are supposed to be 7.0 ohms All tested right to spec. 6.9 to 7.0
2 Speed sensors each should read about 1000 ohms, both tested @ 1030 ohms (The manual goes on to say that the Transmission module is looking for 300 to 3000 ohms so I'm in spec.)
Speed sensor air gap is touching then back off 1/4 turn I have verified this on both sensors. On the input speed sensor I have verified that an AC signal is present when running the motor with a meter.
The manual states that the minimum transmission regulated oil pressure is 170 PSI checked at port "D" I have 190 PSI at all RPM ranges.
The transmission has a diagnostic mode that is supposed to aid in trouble shooting. To do this you insert a fuse into the bottom slot of the fuse block in the right "B" post. Then power up the tractor and use the tractor display to enter mode "21" for diag. (push select for 5 sec. a 1 will display arrow down to 21 and hold select for 2 sec) This all works up to here. The module starts T1 test and displays T1 and other symbols to test the display for function. This test works and the display looks normal. To advance to test T2 you shift the transmission from N to R and then T2 will start this works as well. This test is for the gear shifter and must be completed to move on to further testing. The pattern to be shifted is ...
F, F up-shift, F downshift, N, R, R up-shift, R downshift, N
I only can get F, N, and R to display no up shift or down shift. I have completed the patter thinking maybe it just does not display and maybe it will pass this test but no such luck. This keeps me from being able to get to the other tests for solenoids and clutch pedal reading. What seems odd to me is that when not in test mode I can down shift the transmission from the default gear 3 down to 2 and 1 and I can use the clutch pedal to shift from the default 3rd gear start up to 1 as well. This leads me to think they are working.
The manual states that during the "T" tests the clutch must remain in the up position, except for the "T3" test. With the tractor not passing the shifter test I decided that the clutch potentiometer could be disrupting the test and also be why its not engaging the transmission. My dealer had the potentiometer so I went and got one and replaced it and nothing changed in the operation of the transmission or the test.
After all this here is where I am stuck. I have talked to the dealer near me and they have been very helpful to this point but they don't seem confident in diagnoses of these transmissions and I don't think they have much hands on experience to lend helpful knowledge. They have called the factory and a field service rep and added some comments to get us this far. Supposedly the field rep has a service tool of some sort to talk to the Twin Disc transmission, but they are in Illinois or Indiana and I'm in Minnesota. Can someone shed some light on what this tool is? Has anyone had experience with these tractors and transmission diagnosis? | |
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Versatile 340 with Twin Disc power shift will not move.
