I have read several posts on these machines having the same problem as i am having and looking for some more ideas. As soon as the machine is started it goes under load and labors the engine with all levers in the neutral position and park brake still on. Can hear oil running over the relief in the valve bank which eventually adds to extra heat. Machine operates very jerky. I have unplugged all sensors with no change. Years ago we blew a hose down by the drive motor and replaced the hose and it fixed this problem as we had the same problem years ago. This time I do not see any failing hoses to the naked eye and not sure if oil even flows down there upon initial startup in the neutral position. After running it for several hours it sometimes will all of a sudden quit hissing and work right. Looking for some ideas. Also travel motor speed selection does not work as well when this is happening. Thanks
Check all the fuses are good, check the 2 stacked controllers behind the seat are powered up. They should each have a red light flashing every couple of seconds. Search for posts by LACHAU . He has many excellent posts on how to accurately troubleshoot these machines.
Ok will do. Thanks for the info.
You swap the wires of these 2 solenoids to try first, if it doesn't work then swap the 2 solenoids later.
Ok. I will try later today. Thanks
By the way, do this to see if the machine gives you any errors.
I don't have a Dr. Ex connector but wondering if I can just use 4 test lights and count the blinks
All Hitachi EX120-3 machines have Dr.EX connector. You look at PVC controller. It is an extension cord from the PVC controller which is the connector to connect to the Dr.EX adapter.
Ok yeah I seen the connector on the machine but I don't have the adapter unless I'm misunderstanding what the adapter is. I assume that the adapter has the lights in it that blink?
Oh no!!! You just need to short-circuit pins 2 and 4 and then read the blinks of the LEDs on the PVC controller.
The pvc flashes 4 times and then pauses 3 seconds and then 4 times again and continues to repeat that
Also switched the wires on the solenoids and then switched the solenoids and made no difference
You record a clip when the PVC controller gives the error, let us see what it says. Error number 4 is an error related to the EC motor controller. It can't produce disease symptoms as you described before Now to the next step: you test to see how the situation is the wires and plugs from the PVC controller to 2 solenoids at the main pump; the wires and plugs from the PVC controller to the DP sensor in the main control valve.
Ok. I tested them for voltage the other day and the dp sensor was getting 5 volts and if I remember correctly the ones on the main pump were getting 28 volts but I will check again
Also should mention that the drive motors switch to rabbit speed and back to middle speed but do not switch between low and middle. I know middle and low work together and I believe high is separate. Problem lies between low and middle
Yesterday I had to use the excavator and it was running on the warmer side due to the engine laboring more with the hydraulics doing whatever they are doing. After about probably 2 hours the hissing noise stopped and the engine quit laboring and cooled right down to normal operating temperature. Also the low speed travel mode worked again. Could I have a valve possibly sticking? I know today it will be back to laboring again until it is run for quite a while. Any thoughts?