Hey guys having an issue with an older Hitachi excavator. The machine went into major failure mode best i can figure after the Angle sensor shorted out. Hydraulics very very slow. Would build pressure like it should just pump output was minimum. While diagnosing the machine i also found a shorted out pump high speed solenoid. So ended up replacing both pump solenoids. When the angle sensor shorted and before it was replaced it killed the power to the PVC box. I opened the box cover to check for damage while the bad A-Sensor was still plugged in and the large R1 resistor was so hot it put a blister on my fingers! Unplugged the A-sensor and the PVC LED lit back up and started flashing at a normal interval. So replaced both pump solenoids, the angle sensor, checked all fuses and checked codes in the PVC. Fired machine up and moved slowly for the first few moments but started getting faster and faster until it started stalling the engine out with the hydraulics the pump went to full swash. Rechecked the codes and found code 26 pump control abnormal. Also has a code 22 for DP sensor but im not concerned with that at the moment as i have worked on this machine in the past with that unplugged and operation was normal. My concern is that the PVC has been damaged by the shorted out sensor and will need replacement. Anyone ever ran into this before??? Like i said before the machine when fired up hydraulics will run slowly but then after a few minutes the pumps are at full swash and start bogging the engine and stalling it out. Thanks in advance for any help!
Have you properly calibrated the angle sensor when fitting the new one?
Yes it has been properly calibrated twice just to make sure.
Should be noted also that the #1 displacement solenoid is getting very hot in a short amount of time also
I think you may have your fault codes mixed up. Fault 22 is for abnormal pump control. This fault code is a calculated code. As in, it doesn't take one specific fault to show this code. If any of the sensors display a fault then this code could appear as well. It states in the service manual if this code 22 is active, troubleshoot and other fault codes first before working on code 22. The fact that 26 for the DP sensor open circuit, i'd concentrate on this fault first. If you have a manual follow steps for code 26.
Yes i said it backwards 22 is pump control and 26 is dp sensor. I found the main culprit though. 1 of the pump solenoids was bad right out of the box. Swapped it with the good used 1 i had and problem went away. Now got to do some tracing to fix the dp sensor issue.
hi.. check the connections of dp sensor with this chart.
Turned out to be garbage chinese angle sensor that i used. Also a garbage pump solenoid too. Will never use chinese parts again too much headache. Even though the angle sensor and 1 solenoid cost 1250.00 from john deere. The machine runs like it should now. Also repaired some brittle and damaged wiring.
same problem. I also used Chinese 5 DP sensors, 2 pump solenoids and PVC box.but I couldn't get the machine to normal condition, so i put a manual kit.now machine is slow but can work. This is original PVC box. Power resistor burnt out This is Chinese PVC box. some parts I had to replace within few days with original PVC box
ROM chip I replace with original some boards too
I found a original used DP sensor. now I need a pump solenoid, please could you send a place to buy a original pump solenoid.? and upload a image angle sensor and pump solenoid that you got from john Deere.
i also have the same problem and found this you tube video and went to this area to mess with it nothing happend not that im saying wont work but what i found out is after un plugging and replugging i think my problem was a bad or dirty connection??? just thought id chime in lol Good Luck to all