imgonnadigtochynaa
New Member
I'm working on a 120-2 for a friend.
It was sent away to hitachi and a new pump installed for a constant full stroke issue.
I found the angle sensor installed wrong, then found it sending erroneous signals. I replaced with new and set it to 4.40 at full swash.
I found the pump control valves not getting 24v, the relay was not on, did not have a good ground. I then traced the harness to a bad connection on the floor behind the seat not sending ground to the relay and a portion of the pump control box, corrected and Relay started working.
While i was at it, i replaced the speed sensor, and the pressure sensor.
I've inspected every wire in the cab.
I checked the codes by jumping the Dr.zx connector, I get code 20 on the pump box, and code 4 on the engine box.
I removed and inspected all wires and connections between the boxes by continuity, aswell as opening up the boxes and thoroughly inspecting the pins and circuit board components visually.
I also now notice, the relay for the pump control now powers up for about ten seconds when the machine starts and then clicks off. Stopping power to the pump control valves. I beleive controlled by the pump box.
Could this be caused by the speed sensor or wiring? It is new but untested at the pvm. I have verified the sensor voltages are intact reaching the pump computer, but not tested the speed sensor as it's more of a pulse than anything.
The auto idle, and engine mode functions all work good.
Just stays at full stroke all the time. No matter what.
Unless you swap the 2 wire plugs to the pump control it goes to no swash (my understanding is proper)
Not sure where to look next beside blindly throwing pump control module and engine control module on.
It was sent away to hitachi and a new pump installed for a constant full stroke issue.
I found the angle sensor installed wrong, then found it sending erroneous signals. I replaced with new and set it to 4.40 at full swash.
I found the pump control valves not getting 24v, the relay was not on, did not have a good ground. I then traced the harness to a bad connection on the floor behind the seat not sending ground to the relay and a portion of the pump control box, corrected and Relay started working.
While i was at it, i replaced the speed sensor, and the pressure sensor.
I've inspected every wire in the cab.
I checked the codes by jumping the Dr.zx connector, I get code 20 on the pump box, and code 4 on the engine box.
I removed and inspected all wires and connections between the boxes by continuity, aswell as opening up the boxes and thoroughly inspecting the pins and circuit board components visually.
I also now notice, the relay for the pump control now powers up for about ten seconds when the machine starts and then clicks off. Stopping power to the pump control valves. I beleive controlled by the pump box.
Could this be caused by the speed sensor or wiring? It is new but untested at the pvm. I have verified the sensor voltages are intact reaching the pump computer, but not tested the speed sensor as it's more of a pulse than anything.
The auto idle, and engine mode functions all work good.
Just stays at full stroke all the time. No matter what.
Unless you swap the 2 wire plugs to the pump control it goes to no swash (my understanding is proper)
Not sure where to look next beside blindly throwing pump control module and engine control module on.
!