just bought a 94 model 490e jd excavator it throttles engine up when you walk it but it barley moves until you pull the stick all the way in and keep pulling the joy stick and then it walks fairly fast.
Check the propel pressure switch.I can't remember where it is but sounds like nothing is telling the computer that you are using the propel and it will not tell the pumps to stroke. Follow the pilot lines under the cab for the propel to the main control valve.If there is a plug with 2 wires coming from it in the circuit then that is thePPS. Swap it with another p switch ( behind the cab ) and see if the problem goes else were.
there are two valves behind cab with two switches on each, each have two wires, found a valve block under the cab that had two switches on it also and one was unplugged, plugged it up and it allowed the engine to throttle up when I walk machine but it still barley walks until I pull the joy stick to curl the stick in and keep pulling it while I walk the machine.
also I unplugged the switches behind the cab and walked machine with no change
Hook a switch(on/off) up to the one that was unplugged and try propelling turning the switch on and off. Don't hook to the switch,hook up to the harness.
the inside of the plug was clean so it has not been unplugged long enough to get dirty, what should that test? are you thinking the pressure switches in the blocks may be bad
Just the propel switch.Swap it out with another switch and see if the problem changes.Also look at the harness.
do you know where the propel switch is located exactly?? I have a test and repair manual coming in a day or two
Are all other functions are normal? If they are then check the solenoid behind the cab near the control valve check the resistance over it and then for power at the wires. It will have a steel line running to the propel spool. If it tests good then you need to tee a gauge into that line and read the pressure. Its the proportional solenoid for the travel spool. They are adjustable and I have seen them stick. If this is good you need to start checking load sense pressures. I think what is happening is something in the hydraulic side is affecting the electrical to the pvc and it is not stroking the pump.
Guess i have checked about all i know to check, wires are good from pvc to both travel and speed solenoid's did not pull solenoid valve spool's not sure of what i will get into pulling the spool's, checked and cleaned load sensing shuttle valves, rebuilt rotating manifold , may need to try another pvc?? Guess i can pull the solenoid spool and see if its stuck or a spring is broken??
If you tee a gauge into the steel line from the proportional solenoid and read what that is doing we can tell if the solenoid has an issue, you will need a short length of hose with 6 jic ends on it and a tee. If I remember correctly you are looking for around 400psi. When I had one stick it was at 780psi and would not adjust that's when I carefully cleaned it and it worked. Did you check your solenoid resistance? Looking for 23ohms Are any other functions slow? Did you find any debris in the load sense shuttles?
Solenoid was at 21 ohms, nothing in the shuttle valves, no other functions are slow, it crawls extremely slow, except when you crowd the stick and keep pulling the joy stick then it moves faster, the speed control lights work but still hardly no speed
Tee a gauge in before you take it apart, then if it needs cleaned you know for sure and where to set it.
Are you talking about the pilot line off the top of the solenoid bank ?
Should go to the propel proportional solenoid to the middle of the control valve on the propel spool.
Thanks , for the help, will check tomorrow and report back
Did you get a manual by any chance?
Made up a test gauge this morning and put it in line from the propel solenoid to the main valve bank and started engine, pressure was at 800, goes down to about 650-700 for a second when i try to travel but spikes back up even while traveling
And that is the line in the middle of the control valve not the top or bottom correct?
Got it it was 7-800 psi inner spool seemed to be stuck, broke the small diaphram looking ring on the inner spool, wondering if it is a hafto-have because the only way to get one is order a whole solenoid with inner and outer spools and it is 750.00
Looks that way. Item 2 correct. Its the small part inside the solenoid that broke correct? If it is, that is the piece I have seen stick too.
Found a couple on ebay. I have never dealt with either sellers. I will check price tomorrow. http://www.ebay.com/itm/Hitachi-exc...336-/251384254252?hash=item3a87ab4f2c&vxp=mtr http://www.ebay.com/itm/Hitachi-Pro...Parts_Accessories&hash=item231db05ed3&vxp=mtr
Yes its a rubber part on the back of the inner spool, breakdown does not show it ,the inner spool was stuck in the outer spool
Put it back together without the seal in it, (took another one off to look and it had no seal) seems to work now , makes a hissing sound in forward but not in reverse also no pilot pressure now, gauge may be stopped up, guess it has to have pilot pressure to work so i guess its the gauge will crack line on test gauge and run it and see if fluid comes out, the speed 's do not work, guess i will take that solenoid off tomorrow and check it. Thank's for all your help!!
Have you ever ordered anything direct from hong kong like that?? Kinda scares me, would be nice to have an extra one though!!
I've never ordered parts directly from Hong Kong like that for something so pricey. I've ordered a couple parts for a laptop but that's it, shipping was cheaper than from the states quality was same as oem. Some other people on the forum have though. I checked his feedback no negative and he's been a member since 09 Id say take the chance http://www.ebay.com/itm/Hitachi-exc...384254252?hash=item3a87ab4f2c&vxp=mtr&afsrc=1 . Id replace it with new and adjust it properly but that's me. I think what that valve does is creates a differential pressure between pilot to allow the dp sensor to stroke the pumps if it sees equal pressure (like what yours did) then doesn't stroke the pumps. If someone can correct me on that I would appreciate it though but its all that makes sense to me at this point. Any other questions let me know. I will get a price tomorrow.
Thank you for your help, are you anywhere close to me?
Going to check for used parts at a couple of places first but may order a couple from that place they cheap compared to j.d.
I'm approx 2600 miles from you. I'm not sure what's around you for used. Those ones from Hong Kong aren't a bad deal but looking at the pictures I assume they are used or at least new take offs because of the paint on them but for the price, you cant argue. Looks like that is a fairly common one on your machine. Looks like boom, arm, swing, bucket and propel all use the same one.
Going to check a couple of places for used before i order those first. Thanks again for the help!
Yes their are several that are the same wouldn't hurt to have an extra one laying around
To answer earlier question, yes i got a test manual and a service manual, there is a wealth of info in there, well worth the money!!
So you got the diagnostic flow charts, if you follow the procedure for tracks do not move, it should cover the adjustment procedure for that propel proportional solenoid. The way I did it was run with gauge in and turn adjusting screw until I reached 398psi and called it good. Worked fine after I had cleaned out the valve and readjusted it.
Yea still got the gauge hooked up, will set it if it needs it , thx again!
Is there a way to bleed the air off the pilot system, i had checked the filter by the pump and got air in the system,i guess thats where it came from?? Not sure but its making some functions slow bled some from the solenoid valve pilot lines also the engine is pulling down some when i dig is that normal?
Shouldn't be any air in the pilot system, check the suction at the pumps. Engine pull down is normal but how much is happening? Could it have low power in the engine? Have you played with the angle sensor at all?
Yes i moved the angle sensor but it did not seem to make much difference
I also drained the hyd tank and replaced the fluid it had some moisture in it, may have gotten air in it from that also. Which two wires do i use to check the voltage on the angle sensor to set it?
That will affect pulldown so could the engine. Check that you are reaching full rpm. 2350 rpm in p mode. Could have worn linkage bad fuel etc. I would make sure you set that a sensor back to spec as per the book. Deere spec is 4.40 vdc if you want it to work a little harder set it to 4.45 vdc. Don't go over that 4.45 as the pvc will destroke the pumps too soon
You bleed the pumps right as per the operators book right? You have the book so read through it before you adjust it but in short disconnect pump displacement solenoids and wait 5 min and then back probe the to wires going into the angle sensor. Adjust to spec
Did you ever get the machine figured out i'm having similar problems?