I have a Hitachi EX120-2 with hydraulic problems.

[SILVADARIO]

Hello everyone, I want to share the progress of the excavator maintenance. I checked all the wires of the connectors mentioned above and they were fine. After much checking, I needed to replace the angle sensor because the voltage did not exceed 2.1 V. Error code 5 disappeared. 31 was a false contact in the sensor, but code 22 remains.
When the engine is started while the hydraulic oil is cold, any function that is activated at the end of the engine cylinder stroke continues to stop immediately. However, after the oil heats up, this problem disappears, but the excavator loses power to the point where it cannot move. I removed the PVC controller connector and checked the grounds and they are all in order, but when I checked No. 46, there is no power (+). The fuses are all good. My question is, can I put another wire outside and place it directly in the fuse box or do I have to put it somewhere else? Please, I need help.

 

[Diesel Dave]

I removed the PVC controller connector and checked the grounds and they are all in order, but when I checked No. 46, there is no power (+). The fuses are all good. My question is, can I put another wire outside and place it directly in the fuse box or do I have to put it somewhere else? Please, I need help.

Do you have 24V(+) at PVC pin 37 ?
The schematic shows a short jumper from PVC pin 37 to PVC pin 46.
.

 

[Diesel Dave]

Hello everyone, I want to share the progress of the excavator maintenance. I checked all the wires of the connectors mentioned above and they were fine. After much checking, I needed to replace the angle sensor because the voltage did not exceed 2.1 V. Error code 5 disappeared. 31 was a false contact in the sensor, but code 22 remains.

Were you able to adjust the angle sensor to 4.4V as per the angle sensor adjustment procedure in the manual ?

 

[SILVADARIO]

yes Diesel, I have 24v on pin 37, the angle sensor was adjusted but with 4.39v I think it is within tolerance.

 

[SILVADARIO]

Another thing I forgot to mention, when you turn on the excavator, solenoid no. 1 has 24v and no. 2 has 19.8v constantly.
And what I understood from the manual is normally inverted and with 24v

 

[Diesel Dave]

Another thing I forgot to mention, when you turn on the excavator, solenoid no. 1 has 24v and no. 2 has 19.8v constantly.
And what I understood from the manual is normally inverted and with 24v

The voltage should be the same. The schematic shows a jumper between terminal 1 on Solenoid 1 and terminal 1 on solenoid 2.
Replace the jumper.

 

[SILVADARIO]

Ok, I understand Diesel, thank you very much, I'll go there tomorrow to do this.

Regarding pin 46, it has already been resolved, it was a connection problem between the wire and the terminal.

 

[Diesel Dave]

Regarding pin 46, it has already been resolved, it was a connection problem between the wire and the terminal.

Did you gain any performance or were you able to clear code 22 with lack of 24V(+) at pin 46 being resolved ?

 

[SILVADARIO]

Hello, unfortunately not. I suspect that the new PVC controller has a problem. I opened it to check internally and observe all the components and visually they are fine. I suspected the power transistors because without working (only 10 minutes on) it reaches a temperature of 47°C, while the local temperature is around 8°C. It is winter.

 

[SILVADARIO]

I ordered another one from another supplier in China to test.

 

[SILVADARIO]

Hello to all friends and bosses!! I managed to solve the problem, the last problem with the excavator, I replaced the controller I had previously purchased with a new controller, now the excavator is working normally.

Conclusion, the solenoid valves had low resistance which caused the original controller to burn out, the original angle sensor was returning at most only 2.2v, I replaced the solenoid valves and the angle sensor, the voltage of pin 46 returned to normal after resolving a false contact between the wire and the connector.
And finally, the controller I purchased was not working normally.
Many thanks to everyone who helped, Diesel Dave, thank you for your time and dedication, I also want to thank Mr. Makar Samarskiy for his help outside the platform.
If you have the opportunity one day, we can have a coffee!!

 

[Gary Layton]

Thanks for the follow-up. Good info.