Hitachi EX 120-2 Gremlins

As directed low RPM had 3.57 V AC on P high Rpm had 4.52V on speed sensor.

After back probing ground on PDS #2 furthest from engine hydraulic angle sensor did not drop below 1V AC stayed at 4.4V. As it pertains to speed sensor it did increase as RPM increased for example lower setting 3.57 AC voltage mid range 4.37 an high or P 4.57 AC voltage.This was with "switched" powered and ground to terminal #3 of Relay. Still no change in function. Did order Dr Ex and speed sensor yesterday. With key on I hear what sounds like fuel pump sound but my hearing is not great and can't confirm. Is there an internal fuel pump? Light still flickering on PVC.R

Rash said: After back probing ground on PDS #2 furthest from engine hydraulic angle sensor did not drop below 1V AC stayed at 4.4V. As it pertains to speed sensor it did increase Click to expand... If you had 24 volts at PDS furthest from engine and provided a ground to the solenoid the pump should have shifted to minimum displacement and angle sensor output voltage should read approx .6v-1.0v dc . Try the same scenario above but also unplug the wire harness from the PDS closest to the engine.

Dave, for clarity when I added the new ground in the Relay #2 the voltage at PDS #1 and PDS #2 both went from no voltage to 23 V this would be the PDS#1 yellow on PDS #2 so this workaround ground to terminal #2 of Relay solved the lack of voltage on high leg . On the low leg the red/blue I had .2 V of PDS and Yellow/Black had 1.5 v is this normal or acceptable? Any issue with 23 V NOT 24 V? Will run the test you suggest next trip out Dr Ex should arrive possibly tomorrow and if it doesn't I likely will get back to the Mountain Monday.Thanks R

Rash said: Any issue with 23 V NOT 24 V Click to expand... No. I assume you have approx 27 volts at the battery with engine running ? . See the electrical schematic from the manual. Yellow black supplies 24v to both PDS. For clarity the solenoid closest to the engine controls the pump maximum displacement hence “UP“ shown on the schematic. The solenoid furthest from the engine controls the pump minimum displacement hence “ DOWN” shown on the schematic. Yellow terminates at PVC terminal 103 which controls the ground of the “UP“ solenoid. Red/ blue terminates at PVC terminal 111 which controls the ground of the “DOWN” solenoid Double check that the solenoid

Diesel Dave said: Yellow terminates at PVC terminal 103 which controls the ground of the “UP“ solenoid closest to the engine . Red/ blue terminates at PVC terminal 111 which controls the ground of the “DOWN” solenoid furthest from the engine. Click to expand... Both PDS solenoids have the same identical wire harness connector so with an ohm meter double check at the PVC connector that the above is correct. PVC connector shown in screenshot below. While the PVC is unplugged , check for a short to ground at the same individual pump solenoid wires. Also with the PVC unplugged and with key on , one at a time at the PVC harness connector ground the individual pump solenoid wire coming from the solenoid and check if you hear the solenoid click. .

Dave , I do have 26.7 V at battery which are only a year old held up after sitting all winter no issues . When I initially started testing by jumping the Dr ex plug prior to jumping the ground and "switched power from fuse" with key on,cover removed from PVC checked voltage I had .3v at terminal 103 but did not probe the 111 or any of the lower row but will backprobe 111.The maximum voltage I was able to get was 23.8 V but on numerous terminals voltage was 22.1V and 21.9V this was before I cleaned up EC PVC ground terminals at heater control mounting bolt as well for what it's worth. R

I wouldn’t get too hung up on voltages at the PVC. I would focus on what I suggested in post #26. You might as well check everything now cause I guarantee you will be checking it all eventually.

Great advice will follow suit, much appreciated R

Finally, got the Dr Ex over a week behind. Hooked it up and it would not communicate with machine. Had continuity to pin 103 and pin 111. No power to either PDS with it unplugged. Did run hot wire to PDS solenoids and did hear click when grounded so they appear to be functional. Re inspected the PVC and it no smoke or obvious smoke or burned areas. With the PVC flickering and unable to communicate with Dr EX any thoughts?

I think you need a PVC.

Probably China version is all that's available. Was thinking Fday parts. Any suggestions? Thanks R

I know guys that have bought from Friday and Sinocmp

Got one coming from Fday. Will update when installed.Thanks Dave R

Finally got new PVC hooked up and got 3 codes initially 22,34 and 36 with Dr Ex.According to earlier comment on another thread " Ex 120-2 throttle problem" by wide open will looks like Diesel Dave indicated to disregard code 34 and 36 as this is a dash 2 and not applicable. Was able to clear out the 22 code using the " B" and ""A" procedures with Dr Ex. Machine dogged down when under load on all functions. With machine on P hydraulic activated but not on use Actual engine speed 2080rpm,differential pressure(dp) 2.60 mpa, pump delivery pressure 10.5 mpa,pump displacement angle 21.4 degree,pump displacement angle (apr) 5.0degree.The throttle stop was maxed out against stop to achieve 2080rpm for what it's worth. At end of day after numerous test it then thru code 29 after I adjusted the angle sensor . Also checked 5.0 V at angle sensor and pilot pressure. Code 22 was consistent reoccurring code.Hopefully this info will indicate further diagnostic procedures to de gremlin. THANKS R

I assume code 29 was created when checking the angle sensor voltage. You may have inadvertently shorted out the middle signal wire. Check the codes again to confirm code 29 is gone. In regards to code 22, remove the 2 pump displacement solenoid valves to check them for internal leakage. Apply air pressure to one of the two ports on the solenoid valve, there should be zero air escaping at the other port. With no hydraulic functions in use , the pump delivery pressure should only be approx 0.6 mpa. Did you replace the sensor already ?

Thanks Dave, I still have one new pump displacement solenoid one old one currently on machine. I have one old one and one new one hear in town and will test before going back to mountain as was unable to test before because I didn't have the right air chuck. Is 2080 RPM to low? Although I treat my diesel I thought I would replace fuel filter in case of parafin build up in filter if fuel wasn't treated enough maybe get up to 2250 RPM range.Did check voltage at pump displacement solenoid 1 and 2 and both were in the 26 volt range for what it's worth.Believe I read a post about the o ring leakage on pump displacement solenoid so I'll double check those. Could the high pressure be caused by leakage of o ring? Could you clarify when testing that I should activate hydraulics? Thanks R

I want to clarify that with no functions activated the pump discharge pressure at 10 mpa is likely OK because the hydraulic pump is in maximum displacement (24 degrees). Will see what it is when the pump is being controlled normally and is at 5 degrees. I think the engine rpm is low (2080 rpm) due to the hydraulic pump being in maximum displacement. A leaking oring at the pump displacement solenoid mounting could affect pump performance but there would also be an external oil leak. You don’t necessarily need to activate the hydraulics when testing with the pilot controls in neutral. .

Thanks Dave, I assume the next step is to check for air leaks and see if code 29 clears.I will put new PDS solenoid on and if that doesn't correct I'll put original old ones on. I did test all and could hear the click of each solenoid in previous test. On the pump displacement solenoids 1 and 2 what reading should I get for voltage on the neutral or ground wire? If my memory serves me correct I seam to remember both wires having 26v when running. Is running at 10.4 mpa likely the reason for overheating?Thanks R

Also wanted to add had 169 liter's per minute and took pictures of all other functions on two different test if any of that information is needed? In addition I adjusted the angle but believe 4.1 is target voltage key on not running? Pump displacement control angle signal Apr was 3.1 on one test and 5 on another.