Been awhile since I've posted but I've got one stumping me. New Holland DC85 - Ser# N8DC858282 - 4BT Cummins with computer controlled hydrostatic drives The machine basically has a mind of it's own when you try to go forwards or backwards. Forwards, it travels straight fine but does not want to turn, sometimes it might turn better than others but for the sake of description, it does not turn like it should. Reversing is almost impossible, sometimes it will reverse slowly but only on flat ground with no load being put on machine. In forward I'm getting 2700 psi out of the LH drive pump and 1800 psi out of the RH drive pump In reverse I'm getting only 600 psi out of the LH drive pump and 600 psi out of the RH drive pump, which is probably why it won't back up. I have the software to monitor the status of the controller. It has no codes except for a speed sensor every now and then, the sensor has been replaced and the wiring checked. The joystick is showing that it's reading 100% duty cycles in every direction and the module is showing maximum outputs to pump control solenoids when controls are in max settings. What am I missing? I'm leaning toward bad controller, the pressures aren't to spec but every once in awhile a pump will stroke up and go to 3000 psi, but never in reverse, which is odd. Any CNH guys with tips?
Is the oil full. Have you done any repairs in the last little while. How many hours on the unit, have the filters for hydraulics been done, how about suctiion screens? Have you tested for pilot pressures, how do you know if it is not some wonky thing like an alternator sending too much ripple voltage that computer won't tolerate. Takes 2 minutes to test. Do you have a repair manual as not likely anyone else will have. Pilot control valve would probably be good place to test. Have never worked on one, just throwing suggestions. Please tell us all the stuff you have done. Simon C
Oil is full. 5,000 hrs on it. Customer bought it like it is and we have no history on it. It doesn’t have a pilot system, just electric solenoids that move the swash plates in the pumps. Blade control is all linkage hooked to a valve. Voltage is 13. I don’t have a service manual, the dealer doesn’t have a mechanic with any experience on these.
Whelp, if module is saying it’s getting full swash plate movements and is reading full joystick control, then I would agree with you on the bad controller. Espescially if you have verified pressure are not correct but the controller think they are.
Before buying a computer I would remove and cut open the hydraulic filter, squeeze the paper to see what is in it. If something is coming apart, you will not need a computer till all the repairs are done. Way cheaper than computer and if power is at swash plates then maybe something is jammed or worn out. Simon C