Hi Guys, I have a 1996 Hitach EX200-2. I have owned it about 6 years and repaired it multiple times. Recently I was building a road, machine was running perfectly. Then it started to blow to the fuse for the EC motor. I only had about 50' of road to finish so i continued replacing the fuse. Before i could finish the pump went to full swash and would stall the machine with any hydraulic function. Plugging in DR.EX i found i have Code 31 and Code 22. Open circuit on hydraulic temp sensor (found the wires ripped out of it), and abnormal pump control. Would the open circuit on the hydraulic temp sensor cause the PVC to shut down and stop controlling the pump?? I have tested the A sensor (since the pump is already at full swash) and received 4.41v at the center pin. I tested both high speed solenoids and found the one toward the engine (i believe #2) was out of spec. I purchased and replaced the solenoid with no improvement I have tested and confirmed 24v at the yellow black wires at each high speed solenoid with the key on and relay engaged. Using the test harness with light from Deere I was able to find that the solenoids are getting no signal from the PVC to actuate when a function is made with the joysticks. From what i have ready the PVC sends ground signal to solenoids to actuate, is this correct? When machine is running using Dr. EX at idle i get the below readings. Looks to me like the pump displacement angle is correct (showing full swash), angle control signal looks correct as its trying to reduce the swash angle, delivery pressure shows 5.9 mpa (855psi) at I mode and can only get up to about 14.5 mpa (2100 psi) in P model, DP is maxed out and only drops slightly as the engine stalls. Any suggestions? I will be working on it first thing in the morning.
Does it read engine rpm"s? Check your messages.
Morning @mg2361 , My engine speed is reading, and i believe correctly. It's showing about 650RPM at idle, but i assume this is low due to the pump being fully loaded. Appreciate the message. From the service advisor bulletin you sent, do you have the F1 page, self diagnostics? Also Appreciate the advisor # 51730. From this is looks like my DP sensor is reading corretly as pump is fully loaded and reading is about 377psi. Also looks like my angle sensor (AP) is correct as it shows the pump as full stroke, and i had also confirmed 4.41v witth meter. I will confirm Ssol signal to pump solenoids today, this bulletin really does help explain how this all works together. I will take another screen shot while logging Ssol, Pd, and Ea using Dr. EX. It may assist you gentlemen in seeing what I am missing. From my screenshot above it shows the AP at full swash (23.8 degrees) and the Apr (reading which PVC is trying to set pump to) at 5 degrees. To me this shows that the PVC is receiving its correct information and is calculating the correct output, the solenoids are simply not receiving, or responding. Since I used the test harness between the solenoids and the main harness to verify no signal was coming from PVC should i assume this is a PVC failure? Or could it still simply be not producing the correct output, even though it shows Apr correctly?
So I used most of today to troubleshoot. All sensor check out fine and seem to show good readings in Dr.ex. What I found was the high speed solenoids are not receiving ground signals from the pvc. I check continuity for 101/109 solenoid ground as well as 36/47 control ground. Both were good. When the excavator was running the controller was sending signal for (down) to the solenoids but it would not decrease pump swash. I checked directly at the terminals 103 and 111 from pvc and confirmed I do indeed receive a ground signals, (around .4ohms). I also checked continuity of the wires from pvc directly to the high speed solenoids connectors, this checks out good. I cannot for the life of me figure out why it’s not working properly. If I induce a direct ground signal to 103 or 111 at the pvc I can operate both high speed solenoids, directing pump swash each direction. Which prooves that it would operate correctly, if the pvc woukd drive it. It just does not seem to have enough of a ground signal through the pvc directly. Is my pvc bad?
Why not try to test for voltage drop from PIN #36 to your battery box Ground post, and test for Voltage drop on you Pin# 47 to the same Battery Box Ground terminal. Also check Wires Pin # 101 and 109 the same way. If you are not familiar with how to do we can explain. How much loss are you getting from these essential ground connections to your Battery Ground (Negative post) With the unit running. An OHM meter test will only tell you if you are on the right wire, not how strong it is. You may need some meter extentions to do the test, but best do it before firing off cannon on new computer to find out wires are too weak. Simon C
What he said^^^^ X2. Also, is the LED on the PVC flashing once a second? All your fuses good? Check your messages.
@Simon C - good idea. I will do that today. Is the pvc grounded directly to the battery? Or somewhere in the cab. The symbol on the diagram looks like chassis ground, but I know how these manuals are. I looked for it in the cab but didn’t see it anywhere. I’d like to clean up all the grounding points. Once grounds are confirmed, let’s say I were to inject a known good ground (wire direct from battery to terminals 101 and 109). This should prove function of pvc? @mg2361 Yes sir, once per second on pvc and all fuses have been tested as good. Thanks guys
The PVC will have a ground wire or strap, how the power returns to the battery Negative I do not know, only thing I can tell you is that it has to be clean and tight from PVC or any computer back to the Negative post of the 24 volt batteries in the battery box. So one meter lead will be on the ground pin being tested and the other lead will be on the dead center of battery ground with the unit running. Post what kind of voltage loss there is, also you can run a wire from those computer gronds right to the battery negative post and if all was to work properly you would know your harness or a plug in is compromised somehow. Be very careful to only be on a computer ground going to battery ground cause if you were to go to a computer positive driver to battery ground with a wire the computer would be toast. Simon C
@Simon C Voltage loss test complete and found .023 - .034v loss on all pins mentioned above back to battery ground terminal. This should rule out any bad grounds between the pins and the battery ground, even if it is grounded somewhere in the cab first, correct?
Anyone else have any ideas or should I pull the trigger on a new pvc?
Did you read the "Ssol" with Dr EX? If it is indicating "dn", then I'm thinking yes. Your Dp is where it should be for a hydraulic neutral situation. You have a command of 5 degrees, but pump output is 23.8 degrees, but still no ground to the solenoid through the PVC. Grounding the solenoids at the PVC end of the wiring activates the solenoids, which indicates the wiring and solenoids through the circuit to the PVC are good and can carry a load. Voltage drop of the PVC ground is excellent. Engine rpm is reading and you have a valid "Pd" reading. Have you opened the PVC to have a peek inside? Maybe @Diesel Dave or @LACHAU have something we're missing??
The only thing I have is, double check that the wire from PVC terminal 111 is connected to the (DOWN) pump displacement solenoid valve which is located furthest from the engine.
@mg2361 I did read the ssol and it shows “dn” consistently, but it does not produce a ground at 103 or 111. I can manually induce a ground at the pvc or at the solenoid itself and drive the pump to the unloaded state, but a few functions and its back to full swash again. @Diesel Dave - I was able to confirm good continuity at these wires. As well as minimal voltage loss. 111 is connected to down and 103 to up solenoid. Thanks Guys. I guess I will order a PVC. Dealer can’t get one so China version it is!
Well. I got a new pvc. It is now sending the correct signal to the solenoid valves as I can see 24v at the valve as well as a ground, although it’s not sending a strong enough ground signal to operate the valve high speed solenoid. I can induce a ground directly to the solenoid, and use the 24v sent from the relay and it will fire the solenoid and move the pump swash plate. But just will not do it from the PVC. I am at a loss. One thing I noticed is that when swapping high speed solenoids around, I have pressure under solenoid #1 (up). When I remove the solenoid oil will shoot 5 feet in the air, and doesn’t seem to want to slow down. You have to be real fast when removing and installing a new one. I don’t remember this being an issue in the past. Is this normal, or what would cause this? It’s only under the #1 solenoid (up). Under the #2 solenoid there is not pressure built up.
That is because one of the solenoids has a direct connection to the hydraulic reservoir, which should be under pressure, and the other solenoid does not.
@mg2361 thanks. I got so wrapped up in troubleshooting I didn’t even take the pressure off the tank first ♂️. That explains my mess. Thanks again
Test the solenoids again,the pvc only sends a flickering ground if you held continuous ground they may be fried also new doesn’t mean good any more
Any update on this, i have a ex100-2 with the exact same issue as this. what exactly is the 3rd computer for ? the Computer board controller? does that do anything. Computer Board Controller 4248572
The pvc is the valve controller. It controls the ground signal to the high speed solenoids on top of thr pump, if you have exhausted all other troubleshooting options. Probably needs a pvc.
It’s the controller for the monitor