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Hitachi EX-120 Differential Pressure Sensor Problem

Hammer49 · 2012-04-20 06:38

Does Anyone if u can run the machine with the DP sensor unplugged.No codes from the EC and PVC everything normal.ALL hydraulics real slow,I checked all the pump sensors and all are Ok,even the DP sensor but when i unplug it the machine run fine,I am stumped.I need to finish this job will it damage anything by running it this way.I also hear a hissing noise behind the control valve,I don't know if that's normal.with the DP sensor connected if I go with boom down to lift front tracks off the ground it lift the machine about 2 feet off the ground and stop,but if i hold down the boom control and play with the dipper control I can get it to inch up slowly and the engine is at full power.If I unplug the DP sensor,the boom will lift the machine all the way up with no problem. Thanks

Replies17
  1. #1rgl7262012-04-20 08:49

    try to change you dp sensor.

  2. #2Hammer492012-04-20 13:58

    That switch is around 900 dollars. I like to find a way to make sure that the DP switch is the problem.Is there any way to test it.The voltage on it is 4.5, and when i move the controls the voltage goes lower and bounces around.

  3. #3jaytech2012-04-20 17:59

    dp sensor i saw one on ebay for $300. fits a -2 or -3

  4. #4rgl7262012-04-20 18:06

    you can used a good dp sensor from another good machine if you have. or you can remove your dp sensor and test it on another good machine.

  5. #5Hammer492012-04-21 08:54

    I don't have any other machine to try it on.Will it damage anything running it unplugged.

  6. #6soujit2012-06-28 07:37

    if your machine runs fine without DP sensor than its ok run the machine. but you can fit a manual regulator kit available at HITACHI which will bypass all the electrical system and you can run the machine with calm

  7. #7Hammer492012-07-05 19:55

    Thanks i will look into one.

  8. #8KenAl2012-07-06 08:41

    Soujit. Can you get a part number for this kit and some install pictures?

  9. #9weedwards2012-09-21 21:33

    What is the part number for the manual regulator kit and how do you check dp sensor?

  10. #10weedwards2012-09-23 13:43

    If your remove the DP sensor should there be some oil flow or could the pre filter for the sensor stop the flow.

  11. #11shopguy2012-09-23 20:40

    What trouble are you having to suspect the dp sensor, everything dead slow?To check the dp you need to install a good digital volt meter in the middle wire of the dp harness with it pluged in tellus what you get should be .40 volts key on engine not running ,lets go from there when we see what we got,

  12. #12Myles cooke2017-01-09 09:33

    Similar problem replaced dp ran fine for a day then went back to slow mode anybody know y

  13. #13Lachlan Mackie2020-03-04 21:47

    Lachie

  14. #14Lachlan Mackie2020-03-04 21:49

    Hey shopguy I'm testing a dp sensor I have of a ex120-3 I have got .09v with ignition on. I'm presuming that means the sensor has failed? I can't get any info on them anywere Cheers Lachie

  15. #15mg23612020-03-05 04:53

    Welcome to HEF Lachie ! The spec I have is 0.4 V +/- 0.2 V with a maximum of 1.0 V with key on engine off. If you have an original DP sensor that is adjustable.

  16. #16Lachlan Mackie2020-03-30 22:03

    Sorry for the slow reply. I tested the dp valve and i was getting nothing and if i adjusted it didnt make any difference. I am waiting on a new one to arrive

  17. #17RPMex2020-12-20 17:33

    Lachlan did the new DP Sensor fix your slow hydraulics I’m having similar issue with ex 100-2 and looking for some direction