Last night while I was planting the John Deere 7810 Powershift shifted into neutral. After that I only had 1, 2 and 3 forward and 1 and 2 back. The technician came and replaced the wheel speed sensor but the situation has not improved. The tractor has always worked and shifted well. All the codes pointed to the wheel speed sensor, but any ideas on that would be helpful. Thanks in advance.
That sounds like a faulty sensor. Maybe you have a faulty sensor? I have a 7810 that did the same and a new sensor fixed it, but before fixing it the speedometer was not working. Did yours work / does it work?
Edit: You could check all your connections to your trans. I once had a plug at the bottom of the trans that would not stay connected. The safety bridle fixed that but my symptom was that there was no forward or reverse.
Try 16f, 17f, 18f, and 7R, if those also work then your C2 clutch pack is not engaging. The first thing to try in this case is to change the female valves C1 and C2, if the problem changes to the other gears you have a bad female valve. If there is no change you need to check the voltage of the fema c2 valve, if that is verified you are in hydraulic tests.
I once had a 7800 that would lose a gear block at random times, after 2 years of trouble until it worked and finding nothing wrong again and again, it finally stopped working long enough to discover a bad connection under the dash of the floor on a large connector on the top left of the trans on the main harness that leads to the fema valves.
Sounds like they’ve thrown parts into it so far, now they have to find the problem, if it doesn’t calibrate they’ll have to find out if the problem is electrical or mechanical. Fema valves are pulse width modulated, they don’t show full 12v unless commanded, there are tests for duty cycle voltage, to test the harness you go to a test address (20 I believe) on the pcm and energize the valve (move the shift lever to 5th gear forward to test valve c2) and test the voltage on the valve, if not correct then pierce the correct wire in the pcm and test the voltage there. .
The valves are easy to test, any item does not work just change the valve with a working one that is the same (they are not all the same, C1 and C2 must change) and see if the problem moves or remains the same, there are valves Updated for C1 and C2 so they will probably sell you the next ones. If the electrical part is checked, they will go through pressure tests looking for excessive leakage in the element that is not calibrated,
Drivers are a known issue with early John Deere 7810 serial numbers, I’ve seen several bad ones. In mine, at 7,000 hours, when the controller started to fail, the transmission system would lock up and the tractor had to be restarted to run, especially when cold. The new controller fixed the problem, but then the new controller did not calibrate the C2 because the fill time was too long. I ran all the pressure and leak tests and everything was fine so I went to the dealer, $ 5,000.00 to fix the problem (labor only, not parts) and they told me JD should calibrate the PCU on another tractor and then install it on mine. It looks like the C2 clutch is too worn to calibrate so I guess a 15000.00 bill for the change is in my future. My 7800 had 6000 hours in the first transmission and 6500 in the second, the 7810 has 7400 and does not calibrate.