Sorry about the slow response, but I have been working in Badami and we had no Wi-Fi in the camp I was stationed at. I had to dig back through the cobwebs on this. The 143 & 163H had a software program labeled “Hop-Stop” in AWD ECM. If the controller saw/recognized a rapid pressure fluctuation varying 1200 psi within so many seconds then the system would automatically back the pressure off to the front wheel motors. Whenever the front wheels would hop the controller would see this rapid fluctuation in pressure as the tires would slip then grab traction (creating resistance in the system); as the tires slipped the pressure would drop and as the tires would get traction the pressure would increase rapidly. The AWD ECM would be trying to the change the pressure to the requested amount (depending on the lever position) and simply could not keep up with the rapid changes. Sometimes the bounce/hop was so bad the front tires would come off the ground and this is why they came up with the “Hop-Stop” software. Naturally as the tire lost contact with the ground the pressure would drop to near 0 forcing the ECM to ram up the pressure making the problem even worse; the instant the tire came back in contact with the ground the pressure would spike through the ceiling and the controller would try to ram down the pressure. Deere solved this problem with a speed sensor in the front wheel/wheels and protected it with a very well written patent. If the pressure sensor goes out then the system will shut down to protect itself from destruction. If it were to run without the hop-stop it would literally tear up the front of the machine. When we were testing this in Duluth Minnesota several of the machines blew the Duo Cone Seals before they got the signature map developed. It never solved the problem and I’m sure that’s why they finally decided it was time to pay Deere to use their patent on the M Series. They can test that pressure sensor with ET in just a few minutes. The system is quite complex, but that is the first place I would start looking.
Best Regards, Randy
