Ex100 dp sensor problem

[JDirt]

Hello, I was wondering if anyone knows how to test a dp sensor to determine if it's good or bad? I know these are sometimes bad right out of the box.

I have narrowed my search down a bit trying to figure out my ill running machine. Seems the only change I can make is with the dp sensor. I have 2, the one that came in the machine when I got it, which is not adjustable, and one that I ordered on Ebay which is adjustable.

The non adjustable one, when probed with a meter, the middle wire reads 4.78 volts. Machine symptoms are very slow movements, then when against something (bucket on ground, bottom out a cylinder, etc) pressure checked at the main pump goes up to 5500 lbs and relief valve hisses.

So the adjustable dp, I set to .45 volts key on, which is within specs according to my manual. Symptoms now are: works normal speed but has no power, every function stalls out the hydraulics (not the engine) and the hydraulic pressure never gets over 3000 (actually drops off a bit when the oil gets warm).

So I hooked up a meter while running, non adjustable dp barely changed at all. Adjustable one varies like I would expect it to, but I noticed when a function came under load, voltage didn't stay low (calling for more pressure) it dropped down (around 2 volts) then came back up to 4.2 while my pressure gauge stopped at 2800.

So how should the dp behave? I think when you're digging hard it should stay at a low value telling the pump to stroke more.

Sorry for the long post, any suggestions are appreciated.

 

[dieseldog5.9]

If memory serves me correct, the service manual calls out some voltage ranges for the dp sensor, I do not own the manual, there are a few very talented individuals on here when it comes to hitachi machines especially in that -2 or -3 vintage, give it time they will chime in, my experience is the aftermarket dp sensors are junk right out of the box, been bit hard numerous times, the part from Mr John Deere is $1200 if i remember corectly.

 

[mg2361]

What dash number is your machine?

 

[JDirt]

It's a -3 machine.

I have searched for another dp sensor and got prices all over the place. Ebay and Amazon have them for $60, Finney's is $185, a couple others were $5-600, and I remember when I bought that last one, at that time Deere was $1200.

I would pay the big bucks if I was sure it would fix my problem. Deere usually won't take back electronic parts if the package is open.

 

[JDirt]

Correction, I called deere, now the dp sensor is $1422.

I was studying my manual and wondered about the shuttle valves, especially #7, the way I understand, the pressure going through these is what acts on the dp sensor. Anyone know how to diagnose a bad shuttle valve?

 

[mg2361]

With any Hitachi/Deere of that vintage the first thing I recommend is to make sure all your fuses are good. Then with slow/weak hydraulics or engine stall from hydraulics I recommend swapping your displacement solenoids on the pump around to see if your issue changes. Did you try that? Also if you have the manual it should tell you how to get fault codes without a diagnostic tool. See if you have any codes that might lead you in a direction.

 

[RPMex]

JDirt how did you make out with your ex did you ever solve your DP problem I’m having similar issues with an 100-2

 

[millerJB]

With any Hitachi/Deere of that vintage the first thing I recommend is to make sure all your fuses are good. Then with slow/weak hydraulics or engine stall from hydraulics I recommend swapping your displacement solenoids on the pump around to see if your issue changes. Did you try that? Also if you have the manual it should tell you how to get fault codes without a diagnostic tool. See if you have any codes that might lead you in a direction.

Having a similar issue with a 1992 EX100, some hydraulic functions are slow/weak and choke the engine down. Some functions operate normally. I swapped the displacement solenoids and nothing changed. Wondering if you have any advice on what I may look at next?

 

[millerJB]

JDirt how did you make out with your ex did you ever solve your DP problem I’m having similar issues with an 100-2

Wondering what you may have found? I am also having a similar issue with a EX100. Swapping the displacement solenoids did not change anything.

 

[RPMex]

I’m still not 100% sure what the problem actually was but I changed about every sensor on it as well as the wiring connections. And it came back to life and has been running great until a recent stepper motor issue. Lol what do the codes say?

 

[millerJB]

Thanks! Some of the hydraulic functions are weak and slow and/or choking my engine down. I’ve pretty much ruled out the fuel system after cleaning or replacing everything up to injectors… seems to be hydraulic related I think and I’m not sure what to try next, I swapped the displacement solenoids on the pump and nothing really changed.

 

[millerJB]

Sorry, no codes, the cab electronics are in poor shape, I may have to find a code reader to try to pull any… it is a 92 model

 

[mg2361]

Sorry, no codes, the cab electronics are in poor shape, I may have to find a code reader to try to pull any… it is a 92 model

I answered you on accessing codes on the thread below. You should have started your own thread to keep thing's organized.

Engine almost stalls out when you load the hydraulic's on Hitachi EX200