I have a EX120-2 with a stalling issue when the control lever is down. Been working on bringing this machine back to life after neglect from previous owners. The machine used to constantly stall. I have replaced the pvc, solenoids, angle sensor, pressure sensor, and dp sensor and all wiring (non oem parts). After some work I was able to get the machine to not stall when the control lever is down, but only when cold. Once warmed up the machine will stall in all work modes except for for fine / slow mode. I have dr zx and see that the dp sensor goes to 2.6 MPs (sensor will not read past 2.6) and it stalls and the pump goes to full stroke. For some reason the when looking at the control signal to proportional solenoid it does not say down when this happens. It’s like the pvc is not telling the solenoids to slow the pump. Works fine for about 10 minutes and then warms up and dies. Engine temps goes up too when this happens. What am I missing here. Sensors bad?
Codes?
Did you see this? Deere 490E and Hitachi 120-2 are the same machine, just different engines. HeavyEquipmentForums
So after studying the manual some more and more reading of other posts I was able to determine that the dp sensor was reading 0 mpa when it would stall out and the pvc was not tell the pump to step down. Got to thinking that this means the pressure is high on both sides of the dp sensor (hence the 0 reading and the stalling). So read the trouble shooting section of the manual narrowed it down to this using dr zx to confirm sensor readings of the pump and the dp: So I figured out where the surge relief valve was remove it. Cleaned it and reinserted (well I banged it out against the track and quickly reinserting to avoid massive fluid loss). Fired the machine up and it not longer overheats or strains the engine and stalls. Important to note I bought a second new dp sensor (china version) and did not realize right away they are adjustable by taking out and turning the allen screw on the end in or out (looking for around .4 volts on the middle wire on the harness). Victory!!! Onward to the next major issue key does not turn on engine stop motor, thinking it is emergency relay or stop motor (hoping stop motor since it is cheaper).