I knows there is other threads for this same issue. Im opening this one for tracking what I’ve done to try to solve this issue. I appreciate any help. Yesterday I experienced this issue intermittently. Normal then slow then normal again. I figured it was the throttle cable that was jury rigged because I revved the engine up as high as I could and then the hydraulics sped up again(to actual full speed) Today, noticed the same issue…hydraulics were slow but this time nothing seemed to fix it. Heres what happened today. On Auto Idle: 1. Slow bucket curl in 2. Slow main boom up 3. Arm in and out seem slow 3. Track speed is slow as well 4. Swing speed is fine 5. Bucket out is fine On other modes everything is slow. Higher engine rpm does speed the hydraulics up but not by a lot. It still builds pressure enough to dig a full bucket of dirt and lift as high as the boom can go. Its just slow. Also noticed a “shhhhh” coming from the main valve block when no input is given on the controls. Can’t remember if this is normal. Ive only had the excavator for a week now. One last thing, when the hydraulics were working fine yesterday, I noticed as more load was introduced to the hydraulics, the engine would work to supply more flow(or bog). Now it doesnt matter if I go to dig a stump, it seems to be only operating at a static flow rate. The hydraulic pump and engine don’t seem to be working in unison like before.
You can check for service codes using the red indicator light on the PVC controller behind the operators seat. See the link to an older thread below. Post #14 shows how to enable the self diagnostic which sets a light flash sequence, (if there are any codes). HeavyEquipmentForums . . The PVC is the bottom controller and EC is the top controller. Ignore the light on the EC. if there are any codes ,the light on the PVC will blink in a pattern of long and or short sequence.
I think I found the cable but still having a hard time finding the PVC. Is it below the panels?
This is below the panels behind the seat
Is this it?
The PVC is highlited below.
Thanks! Ill check that later today
Before we go much further , can you post a pic of the top of the hydraulic pump.
Is that out of this repair manual? https://www.emanualonline.com/const...onstruction/excavators&utm_content=Excavators
Sure once I get home Ill post a pic
No, the screenshot I posted was from the Deere online parts catalog. BTW the manual you referenced is for an EX100-1 . The EX100-2 manual you need is Hitachi part # KM104E03 also marked as KM104-E-03
Ah shoot yea I got it thinking I had a -1 from the other post. We figured out it was a -2 actually.
Awesome thanks Im going to get that one
For anyone with the same issue. I found this page in the manual as a good read.
Ignore the hydraulic fluid on the bottom there i had the other side of the hydraulic tank open and it split
Thanks for the pump pic. See if you can pull out any service codes.
No problem im trying to pull these panels off at the moment. I should have it off soon
Ok its operating normally right now. Let me see if I can make it go back to slow
Lol PCV bolt wasn’t tight so the connector was sitting crooked. I adjusted it to sit in the connector and its fixed right now
Something is going on with either the connector or the PCV because I tightened it down and it went to being slow again. Loosened it and push it on the right side of the connector and its fast
Where is there supposed to be a blinking light?
See screenshot below,
I believe this is what is causing the issue. PCV connector slot pins aren’t sitting in the main PCV connector correctly. They appear different lengths. When I push on the connector is fixes the slow hydraulics but if not held in the correct position its either slow or goes to fast and stalls the engine
I believe there are both power and grounds in each end of the PVC /connector. Makes sense that the performance would be wonky with a loose connection. With key on , the light on the PVC and the EC should be flashing approximately once per second indicating that they are powered “on” .
Thank you dave
The pins you have circled , are they locked in that position or can they move in and out ?
I need to unscrew the EC to see the light. I might have to do that tomorrow. Its not just one side of the connector as I thought its both sides as you mentioned about the power and grounds. I have it positioned perfectly to where to problem is gone but the wiring harness connector is definitely not going to sit right while its moving and digging. Any chance you know how I can go about replacing this? Not sure if I could solder or tape it as the position is too specific
Yea I think theyre locked in position
Can you post a pic of the connector face.
What condition are all the pvc controller pins in ? Are all the pins aligned ? What condition are the terminals in on the highlighted connector terminals in pic below ? They look a bit sketchy from here .
When i was looking at the PVC all the pins looked great but those ones that you circled I saw they looked broken on the end. Ill go out and take a pic of the PVC I found a internal wiring harness for $600 but might see if I can try something to fix it
The pins in the last pic look pretty jacked up. Ill try to move them
There are 2 pins in the controller that look badly arc gouged. The larger pin is a ground . See 2 pics below. .
Those are the places I had to hold pressure on the connector too. Do you think I’d be better off with a new PVC then?
I think so if you want to get max life out of a new wire harness.
Ok thanks Dave. I appreciate all the help. Ill start with a PVC for now maybe do the harness down the road. ARC gouged never heard that before. Is that a manufacturing defect? The bolt securing that connector was lose but its hard to believe anyone was below the storage panel because the screw heads were so brittle, ended up grinding them off. So not sure if one of the previous owners tried to fix the pins. Either way glad it didn’t turn out to be an easter egg hunt
Arc gouging is created by an electrical arc due to a poor connection between the pin and the terminal.
Oh ok understood. One last thing. These PVC typically come preprogrammed right? Seen some on ebay for $300 but not sure if I should get from there or fridayparts
Yes the PVC‘s are plug and play . . I will see if I can find a part numbers for the connector terminals,
No, nothing here.
Yea I might just buy the harness sometime soon then. I need to look at the manual some more to figure out where the internal one is going and where it stops
Is there a specific model number for the PVC? I bought one on ebay and the seller messaged asking about what the model number was off my PVC. Its for a ex100-2 so not sure if it matters
It looks like there are (3) possible pvc options . On the top or bottom face there should be a label with a part # .
Ok good to know Ill check thank you
Most Hitachi manuals have very good electrical sections. Did you find the PVC part # ? The part # starts with 91xxxx
Yes the manual is very helpful. After reading through it yesterday everything was making sense with what I was seeing. Not before when I was reading the -1 manual lol. Once I get home Im going to look at the model number then reorder the PVC. I just canceled the other one in case it was the wrong one
I might try to put a little solder on the tips of some of those pins to see if they make a better connection. I had to do that one time for a truck fuse
Nothing to lose.
Hmm maybe I could use a 3d printer to print that connector
Is there anything wrong with the connector besides the terminals at one end protrude a bit further out than the others ?
Heres that shhhh noise I was hearing. Was able to replicate it. You can see in the video how much I have to adjust the connector Honestly not sure. I thought you had a good conclusion with the arc gouging. Some of those smaller pins probably causing issues as well
Going to inspect more soon. Home shortly
Well no i dont think there is besides the shorter pins
@Diesel Dave
Only two things im seeing on this
That sucks. Have another look around where the missing machine serial # tag was below the cab , see if there are any numbers stamped in the frame. .
Ill keep looking right now having a bit a fun since its fixed. I narrowed it down to either this wire im pointing at or that side
I think it might be below the boom on the frame. I have to double check. I got my Dr.zx in today but the software that came with it is out of date. Do you know if I can download the latest software online anywhere?
No help with DRzx here.
Tried looking below the boom for the serial number, couldn’t find it. Might need to get a power washer
Serial number should be here.
The plate isnt there anymore but looks like there might be another below the one on the cab? Ill check. Anyway to tie the manufacturing date and serial of the pump to the current model?
That whole side I was pointing at is responsible for those sensors and power/ground to the PVC. Not sure if its one wire, seemed to be three Either the box wasnt on causing max flow and engine stall with hydraulic input? Box was on but hydraulic was slow Box was on, heard a audible clunk and felt below my feet when i got it the wire position just right like something was turning on - which fixes it
For information only , at Friday parts all 3 Hitachi PVC part #’s sub to 1 aftermarket # .
I could try to look at the EC later maybe has a model number. Those look to be oem. Last thing i can think of is open up the pvc to see if theres anything inside
There is only one EC part # listed in the Hitachi parts catalog.
I wonder if the eBay seller is offering a generic EX100-2 PVC similiar to Friday parts. If so, the ebay selller is wanting to confirm the machine is actually an EX100-2 and not something else . The EC part # is unique to an EX100-2 so an EC part # may have some value if you can find it.
PVC Controller 9131576 9116368 for Hitachi EX120-2/3 EX100-2/3 Excavator CPU Box | eBay Available Part Number: 9131576, 9104907, 9116368, 9131579, 9116366, 9104905, 9133701. Application model: Hitachi EX100-2 EX120-2 EX100-3 EX120-3. Maintenance service: repairing for monitor, ECU computer and hydraulic pump; monitor hours resetting, etc. www.ebay.com Heres the link to what I bought Ok heading home ill check when i get there
Welp valve block just gave out. Its got a crack
Don‘t see the exact crack here , can you clean it and re post a picture ?
Ill run back out there in a couple mins. Heres another pic Its near the DP sensor on the back side of the block
Well maybe its the inlets
Phew Its just the inlet. Just double checked
Maybe there was dirt in the hole when the socket head cap screw was threaded in. Have seen before. Simon C
Ah ok looks to be a new hose so I bet it just wasnt tighten all the way
Now just have to figure out how im going to tighten it. Not sure if ill be able to get a ratchet to fit might have to get my allen set
@mg2361 heres that spot @Diesel Dave Also the EC just had the same marking as the PVC
Control valve serial
Can you clean off the control valve serial tag a bit better , the bottom # will be the part #
Yea im out. Ill grab something better for cleaning off the grime
430 4717
Doing a where used search , that main control valve part # 4304717 is unique to an EX100-2 . So we now know you have an EX100-2 with serial # 31115 and above . See parts screenshot below. .
Great!!
Im just going to plasma cut a square on the wall in front of the pump inlet to the block. Cant get in there with anything without taking the return hose off and some other stuff
going to have a hose and fire extinguisher close by
This is the PVC model number I need to get then. Good find
All we know is the serial # is above 31115 . Could be pvc part # 9116366 also. If the suppliers are only offering a generic “EX100-2“ PVC, the serial # I don’t believe is that critical. I think the only thing that matters at this point is knowing 100% that you have an EX100-2.
Heres one that mentions both maybe theyre compatible with eachother since we know now its a ex100-2
What about the engine serial
@Diesel Dave ah damn o ring
Similiar to Friday Parts the supplier is offering a generic “EX100-2” pvc which should work. I have no experiences with any of the aftermarket suppliers so can’t make any comment/ recommendations.
The parts catalog doesn’t cross reference engine serial # to any machine serial # . An Isuzu dealer may be able to reference an Isuzu engine sn # to a machine serial # that it was installed in.
It happens . I think you mentioned earlier you thought the clamp bolts were loose ?
Yea the two bottom bolts were barely screwed in I dont blame them though because thats a crazy space to get to. Heres what I had to do
The inlet o-ring i measured it out to OD: 1-1/2” ID:1-1/4” thickness: 1/8” They had them at ace hardware
Just letting you know that some o-rings can be the same size but will not react the same under heat. Some get brittle in no time. Simon C
Ok thanks this one is Danco brand. I think it might be for hydraulics
Shoot i dont think it is
Harbor freight had it in this kit, all nitrate based rubber o rings
@Diesel Dave I was looking around the connector some more and I found the connector tabs flip up. Haven’t figured out which wire it is so just ordered the generic ex100-2 PVC from friday parts
Look at the right side plug. 3rd wire from the left looks to be green corrosion. One beside it does not look good either. Simon C
Yea they aren't looking too good. I bet it hasn't been touched in 25-30 years. I bought a crimping tool. Im going to try to crimp new terminals and cut the wires back a bit. I tried seeing if I could narrow it down last night. I was fiddling with the wires one at a time but I think its multiple ones. Its odd because when I tighten the connector all the way to the specified torque it says, I would assume it would fix it and the terminals would have a good enough connection...but if I do that then hydraulics go slow. If I loosen the connector and pull the right side out more then the left a bit...it fixes it. Theres a specific spot though because if it isn't just right the PVC turns off or the PVC will be on but the hydraulics will stall the engine
The juice isn't worth the squeeze at this point just going to crimp new terminal ends. But I wish I knew what it was. Maybe the terminals on the PVC itself could be causing it but won't know until I get the new one in
Since load sensing is active with all modes and uses DP and A sensor for comms to PVC, I think the DP Sensor and/or Power and Ground is whats causing issues. A sensor wires wasn't effecting anything when I was moving the wires like the others were. Whether its on the PVC or connector itself I have no clue. I'm calling it there lol
Alright well fridayparts asked for the serial number. I decided to tear this open to see if I could find anything else relating to a model number.
Nevermind just blew it off with air and everything is working fine now
I don’t see those pvc internal numbers as very helpful at all…too bad
Seriously ?
While we are talking about machine serial #’s . Does the monitor controller have a part # on it ? It sits on the same shelf as the pvc and ec. .
Yea haha blew it off with air tightened it to the torque specified and it was working. Now finally think it just died. Checking to see if it was a fuse. Pulsing Light isnt coming on anymore
Im not seeing one on the outside of it
Ok blown fuse need to find another 1 amp
Yes, don’t install a higher amp one !
That was my fault i shorted the power probing around
Alright its back to being slow. Hooked the wire up to the diag connector. Its blinking blink…pause…blink…blink… then blinks 8 times after
I take that as ec code 1 and pvc code 28 . Can you video that sequence just to help confirm ?
Codes for the hydraulics stalling Codes for slow hydraulics Codes for hydraulics working correctly
For “fast to stall“ video , I read codes 1, 22, 26, 28 . For “hydraulics slow“ video , I read codes 1, 28 . For “hydraulics normal “ video , I read codes 1, 22, 26, 28 . . Per the manual , code 22 (abnormal pump control) is created only because code 26 is active.
Thats what I got too. Weird… i let fridayparts know the situation with the two PVC model#’s. Ill probably hear back from them tomorrow. they asked for pictures of the PVC so hopefully they’ll find something
With the DP and P sensor fault codes found , If I was going to crimp on some new wire terminals at the pvc connector I would focus on the DP sensor wires and the “P “ pressure sensor wires. Where did you find the new terminals ?
Ok ill do those. I got these coming in tomorrow. Not certain if they are the right sizes https://a.co/d/7lQ3JJb
Sounds like you're dealing with a possible issue in the hydraulic pump control system—maybe a faulty load-sensing valve or pump solenoid that's not adjusting flow correctly under load. The “shhhh” from the valve block could be internal leakage or a stuck spool. Also, check for any clogged filters or weak pilot pressure. Worth checking pump sensors or any electronic control issues too.
Correct. Ended up being within load sensing circuit but surprisingly PVC connector was loose causing intermittent connection loss with all sensors/power & ground. I forgot to mention earlier the “shhhh” sound was solved after I blew a o ring in the main inlet hose to the control block. Bottom two bolts weren’t tight all the way allowing some pressure loss. Eventually pressure overcame the o ring and blew the o ring shown earlier in the thread.
Fridayparts said everything I sent them helped them confirm the PVC
@Chris1113 , Related to the Angle sensor and the P sensor
Ok ill take a look. Just Fyi I was pushing some of the terminals in some with one of those hook tools
Just order 12 bottom rollers, 2 top rollers, 2 idlers and adjusters from china. All for $800 + $250 shipping. Learning about how to import into the US. Tariffs might eat me up a bit but still would be cheaper than 2 adjusters off ebay. There is also customs fees and port fees. Might come out to around $1500 total Not too concerned the quality most of this work this excavator will see is digging stumps. More of a project to work on when Im bored and learn about. Ill review them after a year on here to tell yall if it was worth it or not
I did the UC on my 120-3 last summer. I was shocked at how reasonable the price was from the dealer. (12) bottom rollers (2) sprockets (2) idlers (2) chains $5500 for everything and had it the next day. ITR brand
Thats not as bad as I thought it would be. I was thinking it would've been closer to 10k
@Diesel Dave I was vacuuming out all the dirt this weekend look what I found Cant tell if its 31976 or 31576
Good find !…write that down somewhere .
Haha yes its going in a plastic bag in a filing cabinet also took pictures!
It’s me 2 months later. Found out all my sensors were shot. I got a new angle sensor then used two buck converters from Amazon to manually mimic the voltage communication to the PVC for the DP and P sensors. I got new sensors in the mail but the it’s been working fine the way I have it I just haven’t got a reason to change them out. I just having to manually turn the screw in or out on the buck converters to set the voltage I want to the PVC which in turn gives me the load I need. I’ve been doing this for about two months now.
Hey Chris, @dcar and I have been working on a EX120-2 and are questioning a new aftermarket DP sensor that was just installed. The DP sensor doesn’t appear to be functioning as it should. @dcar ordered the same buck converters as you . Can you share how you wired in the buck converter and what voltage was set at to mimic the DP sensor ?
Hi Dave , I used the power and ground going to the PVC to power the buck converter. I just removed the tab on the back of the PVC main connector then in order to remove the pins you have to have like a small L tool to push up the retainer clip holding the pin in from the front, then you can remove the pin from behind 5V supplies the buck converter - it has a screw you can screw in and out to adjust the voltage. Leave it around 2.2 Volts, I think it might work better to have the P sensor on a buck converter to, when you adjust the P volts you want it to be 1.8-1.9 volts for fast hydraulics, if you need more load like going up hill or digging a root I adjust the P sensor to around 2 volts. The hydraulics will be slower but you won’t stall as easily. I found that voltage range has the be lower or equal to the DP sensor but not by a lot because the more you turn it lower the quicker you will stall when you’re doing something that requires a lot of load. i tried a bunch of different voltage ranges and this is the only combination that worked
@Diesel Dave Power and ground for that specific sensor not the PVC as a whole. Each sensor has a power ground and sensing wire going to the PVC to communicate the voltage the sensor is outputting. I had to make these wires. One end is going to the PVC power/ground for sensor then into the buck converter IN side. The OUT side is only the sensing wire back to the PVC
https://www.mouser.com/ProductDetail/Aptiv-formerly-Delphi/PPI0001483?qs=HumNWfwekiGhMmyxdda0VA%3D%3D&countryCode=US¤cyCode=USD Let me double check what terminals I got because I got a few different types
Thank you Chris !
Hello Chris, on the Buck converter where is the screw to set the in voltage? I see the push button pots or are you talking about the tiny screw on top of the blue square thing?
@dcar Hi dcar yea it’s the gold screw on top of the blue square
so set that for the 2.2vdc.? what am I setting when I push the pots and it adjusts the voltage? must be the volts out. Should it be set to anything? You mentioned putting one on the P sensor also. Is that still your thinking and what settings do you recommend.
The voltage you see on the screen will be the voltage that’s going out. Yes set it to around 2.0 to 2.2. I might depend on what your P sensor voltage is. In your case since you just have one mimicking the DP sensor voltage. You might have to play around with the range. I would test 0-5 volts first, see if the hydraulics act different at all
are you back probing the plug to see the voltage in so you can adjust it?
I’m mimicking both sensors in my setup View attachment IMG_0388.jpeg
Okay I put mine at the plug for the DP sensor. I am no electrician and this is all above me. So I need to see where I can meter the voltage in so I can adjust it.
What I did was identify the power and ground pins for each sensor using the manual. I removed the original terminals and crimped my own wires and terminals, then inserted them into the now-unused power and ground slots on the PVC connector that originally went to the sensors. Each sensor normally receives 5 volts from the PVC, and the feedback wire communicates a signal back to the PVC. In this setup, you’re bypassing the sensor entirely. You’re just using the original power and ground wires to feed the buck converter. Once you have power to the converter, you take the OUT terminal and wire it into the sensor feedback pin on the PVC connector.
View attachment IMG_0388.jpeg
on the P sensor the three wires are they the same as the N sensor where 1&3 are the 5v and 2&3 are the signal voltage?
Yea I think so. I didn’t really work with the N sensor much. Is that the engine speed sensor?
right. So I am going to put the buck converter at the plug for the P sensor. 3&2 in and 2 out. The voltage in at 1.8 and voltage out the same
Morning Chris, I guess I'm doing something wrong. I connected the DP sensor wires the power and ground to the IN side and the signal wire to the OUT side and try to adjust the voltage with the little screw but the display doesn't change.
Morning try to change the display I think there’s different options with the black buttons on the sides
Hello Chris, I was wondering if you could call me when you have a minute Dave Carson 1-231-675-7452 Thank you
Hello Chris, I was hoping to talk with you more on these buck converters but I am confused on the voltage in. I think it should be 5.0v in and 2.1v out correct? My P sensor is showing 0.66v with the tractor running and if I raise the boom or other function the voltage goes up to 1.23v