Well the old girl is acting up again. She is a 95 EX400LC-3 material handler. This time it seems one side of the pump is not putting out "much" flow or PSI. The bucket opens and closes really slow. Swinging left or right is slow. The left track is slower also (unless you swing at the same time as trying to travel than it seems to travel at the same rate as the right track, only both are slower than normal). The boom and stick are slower than normal, but not in limp mode like the last time I had a problem, which turned out to be a bad angle sensor that when the sensor heated up it would short out and blow the fuse for the PVC and put the machine into total limp mode. You can read that thread here at this link . Since this is a material handler the functions are a little different than on an excavator. It has a circuit that is electronically controlled to open, close and rotate the bucket using 4 way valves which is operated by pushing buttons on the joysticks. The machine has a three piece boom so the boom and stick circuits are like a normal excavator but the bucket circuit operates the third member of the boom. There is also a electronically controlled flow priority valve which puts 30 gal/min from one pump to a magnet generator with a flip of a switch. This valve tee's into the side of the pump which would normally control the bucket, the side I'm having problems with. The magnet generator will not turn fast enough to generate enough voltage to operate the magnet controller either. (When the generator is on it robs 30 gal/min from one side of the pump, the machine is now acting about in the same way as when the magnet is on, only now it is running much much slower even with the generator turned off) So I'm almost certain the side of the pump I'm having problems with is the side that runs the generator, which is the side of the pump closest to the bell housing. When I turn the generator on now the bucket wont even move and the machine won't swing either way. I checked all fuses which are good. The LED's on the EC and PVC are flashing about one flash per sec. on each box when the key is only turned on and when the machine is running. The auto idle works just fine. The wiring harness for the machine was replace about 1000 hrs ago and is not cracked anywhere that I can see. The pump was rebuilt less than 500 hrs ago. Anyone have any ideas where to start checking?
One other thing I noticed was what I think is an alarm that is mounted up inside the main frame below the engine (square box with holes in it that looks kind of like a speaker) is now making "some" noise when the key is turned on and the engine is not running. I have never noticed that before when the machine was running properly. Not sure if this is the alarm for travel or not. I do know my travel alarm does not sound when I walk the machine or at least it is not loud enough to hear over the sound of the engine it if it is working. The alarm it self might be bad though and that is why I haven't heard it before. It may be making a noise when the machine is running also but I can't hear it over the engine noise.
Swap displacement solenoids, still no change then plug 4P DS connector into 5P DS and vice versa. If your bucket speed picks up then you know you have a control issue, wiring PVC etc... A failed angle sensor can give you similar problems as well, perform same method as displacement solenoid check. If Dr ex or ZX is availible use it as well for faults and a sensor adjustment
I might have an old dr ZX you can purchase if necessary.
Thanks for the reply. I had the dealer come and look at the machine on Monday. His Dr. ZX was showing a code for a faulty DP sensor on the 4 spool side of the valve. So I ran to the dealer and got a new sensor and he installed it on the valve bank and we still had the problem. Luckily I could send that sensor back since he installed it. We then took a ohmmeter to the flow control valve (displacement) solenoids which gave two very different readings. Swapped out the flow control valve solenoids from one side of the pump to the other and the problem moved to the other side of the pump. Funny thing was we were not getting a code for the solenoid being bad on the Dr. ZX, but I'm not sure if your supposed to either. You sure would think you would though. Had to order a new valve since they didn't have one in stock. After being installed the machine is now up and running normally. I'm just glad it wasn't the PVC or a wiring issue. $750.00 for that valve was enough. How much do you want for your Dr. EX. It wouldn't have helped me on this break down (might even of cost me since I wouldn't have been able to return the DP sensor) but would still be nice to have one in the future. I see a guy from China is selling Dr. ZX on Ebay for around $400.00 with shipping, but I'm always a little afraid to send that much money to someone over seas for items.
email me at [email protected] for more info, I have a US version
While the DrEx is a very handy tool, I have made a lot of money chasing after problems made worse from people wrongly diagnosing machines. What I tell every one, you have to have a solid understanding of the Hitachi electrical/hydraulic system for the machine you are working on. You have to know your inputs to the PVC and the outputs from the PVC. You should understand how a fault code is stored. You should have the correct service manual for the machine for specs. EG angle sensor install and setup. Now after saying all that you have a less complicated elec/hyd system that an EX220-2-3 and under. Also to remember is stored fault codes compared to active fault codes. If you key on and unplug a bunch of sensors you will store fault codes. Which I would think is what happened with your DP sensor if nothing changed.
Thanks for your reply. I unplugged all the different sensors on the pump trying to see if that would make any difference in how the pump was working before calling the dealer to come look at it. That I'm sure produced a bunch of codes. When the tech plugged in his Dr. ZX he had a list of about 10 codes which I told him where likely caused by me unplugging sensors and running the machine. He then cleared all the codes and we ran the machine which produced one code for the DP sensor. We then tried replacing the DP sensor with no results. Since the one side of the pump was not pumping as hard as the other I would imagine the DP (differential pressure) sensor seen the difference in pressure between the two sides and produced the code. I could be totally off on that too. Is the DP sensor used to sense the difference in pressure between the two sides of the pump and will then tell the controller to stroke or turn on and off the different sides of the pump to produce the same pressure on each side all the time? Or is that accomplished on the feedback hydraulic lines which are connected to the regulator blocks on each side of the pump? Or maybe both? This is all a learning experience for me so the more I learn about how this machine operates the more likely I'm to be able to hopefully fix it when it breaks down on my own. That phone call to the dealer is a guaranteed minimum $300.00 bill not including the cost of the parts.
The Dp sensor is an input to the PVC and the only codes it will send is open circuit or short circuit. It registers the pressure differential as a voltage to send to the PVC. You can have an extra plugged in and laying there while running and there will be no code. So this is where an understanding of the system elec/hyd real helps. And I am all for people trying to understand there machines. So I would say it was not connecting properly and sending an Open code. Do you remember the code #? The DP sensor measures neutral passage oil and oil going through the Pump Control Valve and the two pressures are differencially measured and converted to an electrical signal. So the Dp sensor tells the PVC what kind of a demand it wants by the valve spools cutting off the neutral flow and sensing a differential pressure. The pressure sensors send a signal to tell the PVC the hydraulic load. The angle sensor sends a signal telling the PVC the swash angle. The engine speed sensor sends the EC the engine rpm then off to the PVC. The PVC figures out what hydraulic load it wants, what engine pull down there is etc and then it sends the signal to the pump to stroke or destroke. Clear? So you can see the many inputs and the output to the PVC just for the pump actuation.
I don't recall the code # that came up after clearing the codes. I just know he said the DP sensor was bad. Which didn't turn out to be the problem. There apparently wasn't a code for the displacement solenoid that was bad. Thanks for the explanation on how the system works.
Displacement solenoids will not generate fault codes specific to itself, you would usually see a code for pump control malfuction 4p or 5p.
Where can I find electrical/hydraulic wiring diagram of the ex400lc3 , I spent over $ 3000 with the dealers to find broken wire on the hydraulic wiring system. With the plans I can do that easily myself ,