New Member long time lurker. Have a Hitachi EX 120-2 with loss of power and the PVC light is flickering not blinking. Downloaded the Manual from Lachau and tried jumped the 2 and 4 wire on Dr ex.port and don't have the analyzer. The EC blinks (4-5-1) and checked continuity between EC and PVC and tested good according to manual but only get flickering light on PVC . Replaced bad Pilot pump solenoid twice ,second time John Deere part . Inspected PVC internally no smoke or any obvious issue visually same as EC. When machine went down the auto idle power down worked now it doesn't although the light display works. Pump Angle (A)sensor 5 v in center wire changes when rotating by hand.Speed sensor and DP sensor continuity and voltage check out. Pump displacement sensors No.1 and No.2 have no power input key on is this normal?Any idea on why PVC light is flickering? Any way to test PVC without being attached to machine? Thanks in advance.
Welcome to HEF Rash . Are you referring to a loss of hydraulic power ?, Mostly function speed is slow ? What are you referring to as the pilot pump solenoid ? I have seen some instances where the pump control relay coil is grounded by the PVC only when the engine is running. Do you have 24volts at the #1 and #2 pump displacement solenoids with the engine running ? Check that the PVC and EC ground wire loop terminals are clean and tight where they bolt to the cab floor.
Thanks for the reply Dave. Loss of hydraulic power, overheats quickly, sluggish on all functions tracking,swing boom up down. I replaced the Pump pressure solenoid with JD first one failed. Had rodent damage on wires to pump pressure solenoid and splice it and worked good for years. Had similar system symptoms which was fixed by rewiring and recently had panel off and got bushwhacked by small lodgepole pine . Bought all new wire harness from China which was to short but used it to replace where rodents damaged wire and plug connector . Where does the EC and PVC ground loop bolt to cab floor is it a separate bolt? Don't have any voltage on #1 and #2 pump displacement solenoids and have two new ones which I put on with no change so remounted original back on.Machine is on Mountain no cell service and I will check next trip out. Was reading post about eeprom reset using uv light would this be worth while if grounds check out to reset PVC to reboot and see if the PVC flicker would clear up to get blink function back?
The PVC and EC ground wire loop terminals bolt to the cab floor at the bottom leg of the cab heater control panel support. Does the engine stall with any hydraulic function over releif ?
Copy that on ground Dave. Yes it does stall and engine dies. When tracking or using all other functions if you give it to much it dies but if just a little it snails along. Was reading another thread which indicated the Pump displacement solenoid #1 and #2 had their own relays any idea where these are located? Also are these not supposed to have 24 Volts engine off key on?
If you have no power at both pump displacement solenoids with engine running , check for power at terminals #1and #3 at the pump control relay ( power to relay comes from fuse #3 ) . Check if there is power at relay terminal #5 ( to pump displacement solenoids) if not ,temporarily provide a ground at relay terminal #2.. Relay terminal #’s and also Relay location and identification in screenshots below.
It should have 24 volts engine off key on but I have seen some aftermarket PVC’s ground the pump control relay coil only when the engine is running.
Per the service manual if you are getting error code 5 and the auto-idle isn't working, you should replace the PVC and EC. The fact that the PVC light is flickering seems to point to some kind of power supply failing internal to it. I'm not following how you can still read codes if it's flickering.
Thanks Dave, I will try that and report back when I get back to civilization. My PVC appears to be original Hitachi tape part and not aftermarket.
Matt, can't read any codes just the auto idle doesn't function when button is activated and on P after not use for short duration. Was hoping to get flicker light worked out so could use blinks for codes. My fear is if I replace PVC what caused my current issue could fry or takeout new one. Shopping for a Dr ex analyzer any suggestions,if you buy one with palm reader ebay are they out of box ready to go? Thanks for the help. R
There was also a service bulletin regarding the pump control relay coil ground that states, ” There have been some situations where the Pump Control Relay initially energizes, but then loses its ground through the PVC and disengages. When this occurs, the Pump Solenoids do not have voltage applied and the pump stays at maximum displacement. However this can be corrected by rewiring the Pump Control Relay using the following procedure: 1. Cut the Yellow/Green wire connected between PVC connector pin #104 and Pump Control Relay terminal #2. Connect the relay side of the wire to a good ground source. 2. Cut the Blue/White wire connected between Pump Control Relay terminal #1 and the F3 EC Motor fuse (5 amp). Connect the relay side of the wire to a switched fuse (such as F10) so the relay only energizes when the key switch is "ON". “
. @Chiefdug bought DrEx with a tablet, info below.
If you shorted the Dr EX terminals to have it blink out codes and it blinked 4-5-1, that would indicate error code 5. The 4 is a preamble saying it's the start of the code readout, and the 5, 1 error codes are related to EC-PVC communication. If it's just randomly flickering though and reading out different stuff than is a different story. Is the EC led flashing? Not sure off hand if the pump relay is supposed to be triggered by key-on or engine-start, but I would hope it would be key-on so that the pump angle could be dropped to the lowest possible setting before the engine started. Assuming you already checked fuses to make sure none are blown, relays would be a good thing to check as Dave said. I understand the worry about blowing up a new PVC, I've heard stories of some of the aftermarket harnesses being done wrong. The palm pilot/reader cable works out of the box
Matt yeah it was the EC blinking those sequences. The PVC flicker only and is my understanding codes only come through PVC hence the issue. When I shorted the 2 to 4 on Drex plug it didn't change anything I believe it was red to yellow wires. I did do continuity test from EC to PVC also and all tested ok. Fuses all tested out and have a Couple of new relays.
Update, performed the test Diesel Dave after cleaning ground to cab floor at heater control bracket which looked pretty good. Then back probed the Pump Control Relay had 26.4 V on terminal #1 and terminal #3 and only .3v on terminal #5 while running. When I jump a ground from battery back probed to terminal #2 then I was getting power to solenoid #1 and solenoid #2 in the 23 to 23.3 v . Machine still had same symptoms snail mode/ laboring with the exception when I would boom up and apply stick out it would after few seconds delay do from snail mode to fast function on boom up although still laboring. In the abundance of caution Didn't splice in and cut wires just yet because the wire was black/white out of F3 and and F10 was dummy no power in my fuse panel and wanted to confirm before cutting wires. If I understand Dave's point of this it is to limit to positive power with key on only otherwise it would be engaged at all times? With key on not running I had 23 v on yellow and 1.7 v which goes to solenoid #1 closest to engine and 23 on solenoid #2 23.3V on yellow/black and .2v on red /blue. The angle sensor had 5.1v and adjusted to 4.4 when I twisted and also tested moving which increased in and decreased voltage up and down. The P sensor had 5.1V in and center wire was less maybe by half but i didn't right down by mistake. The PVC still flickering no change. Also the Speed sensor had input 5 V but don't recall other voltage. I Certainly feel progress was made and hopefully this will help us sort out the gremlins.Thanks for all the help thus far it is greatly appreciated R.
If you Backprobe and provide a ground for the pump solenoid furthest from the engine does the hydraulic pump angle sensor output change to less than 1.0 volts ? . The speed sensor located beside the pump angle sensor is only a 2 wire sensor , check it with a voltmeter using the AC scale. Put the 2 voltmeter leads on the speed sensor, the sensor AC voltage should increase as engine speed increases.
The black/ white wire is correct. Connect it to a “switched” fuse such as the cigarette lighter.
Dave,will change to switched fuse and ground and check speed sensor next trip to the Mountain. Also didn't mention I changed solenoid furthest from engine yesterday with no results but will perform angle sensor test at your direction. Also swapped out relay #8 to EC yesterday after performing tests no change. Thanks R
You can also test the mechanical side of a pump displacement solenoid when off the machine. Put some air pressure into one of the solenoid ports , there should be zero air escaping from the other port.
Will do have dump truck there with air. Just leaving service will report back.Cheers R
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
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
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
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.
Pump angle sensor target voltage spec is 4.40 +/- 0.03 volts. Very likely.
Yes
Success , wanted to first thank Diesel Dave for his generosity and wisdom helping me repair my Excavator. Couldn't have done it without his help as well as the invaluable resource of information on the HEF. Was able to clear code 29 but was getting code 22 consistent . Had two pump displacement solenoids PDS one old and one new in town and had one old one new on machine on the mountain. Pressure tested the two in town both had a slight bit of air at 120-150 psi and took the new one partially apart and the old one fully apart and wasn't able to get old one back to sealing. Went to mountain and installed new PDS for old one on #1 closest to engine and had improvement the RPM went to 2250 and motor wasn't under load and fluid flow rate went from 200 liter/minute to around 43 liter per minute and pump discharge pressure dropped to 3.1 from range from 10.2.The hydraulic functions were slow but machines wasn't laboring or overheating. Changing the angle sensor by hand did slightly improve performance but still sluggish. I then took the old PDS removed from #1 tested it with air and had slight air leak at 120 psi but then mounted it on #2 away from engine and full power was restored on all functions. I then by hand adjusted the angle sensor where performance was at optimal while digging as moving this made a difference in performance. I believe when I got bushwhacked by small pine tree at pressure sensor where rodent damage occurred I took out PVC hence the flickering red light and not communicating with DR EX if not then with me messing with wire( believe MG 2361 mentioned possibility of PVC damage with key on and disconnecting solenoids or crossing up wire on another thread).Replaced broken high pressure solenoid twice one from John Deere after first failed. Bought new wire harness from Friday Parts and this "does not" fit the EX120 -2 as it is two short and main end is not compatible but was able to cut up and replace new end plugs where rodent damage was. Could be that both old PDS solenoids were good and the PVC and pilot pumps sensor was my problem only and replacing the PDS with Friday Parts new ones which one was defective caused my issue after replacing my PVC? Hope this helps others and know I could have done it without the contribution of members at the HEF of which I am grateful. Cheers R
Good to hear you are up and running !