Good morning. I working on a friends hesston 4910 large square baler (serial number is HL00733). This baler puts up an error code of 7 or 6 and then doesn't read any hydraulic pressures on the monitor. I pinned out the harness and the harness has proper continuity and has no shorts. When I switch the load bar pressure sensor wiring from the right to the left side the error code switches from 7 to 8 (left to right). As far as i can tell there is an problem with the pressure sensor. The sensor is inside the load bar which costs $4000. I wanted to know if anyone knows how to test the sensor? Currently it is an open between all four pins. I have attached some pictures for reference. Your help is appreciated!
I am not at all familiar with them. But it seems as though there must be some type of load cell inside that tube. They put it in there so there must be a way to replace it. Load cells have 4 wires. There are specific ohm readings you should get between pairs. Which I can't remember of the top of my head. If you need more information I can search it up for you. If that is what is in there you can get them from most any scale company.
So with opens between all four pins. Are those load bars faulty. Can they be cut open and the load bars alone replaced??
If the problem moves to the opposite side when the wiring harness is swapped it pretty much tells you that sensor or load cell is bad. I guess it boils down to do you want to spend $4000.00 for a new arm or take that arm off and see if there isn't some way to replace it. I do not believe they are welded in there. That will ruin them every time. They almost have to be installed after the arms are fabricated. Load cells are made in many configurations. They are also made in about as many different weight ranges. You really need to know what is in their first. Those things work on millivolts so any type of welding done near them will ruin them from the magnetic field created. You don't happen to have a parts book for this do you.
That makes sense. I guess why I thought they were welded in there is because the parts book calls it an arm assembly and the parts guy said they are welded in. I have the parts book on my laptop and will check later today
Those load cells are very delicate things and very accurate. I find it hard to believe they would be welded in those arms. Also when you buy new ones they will come with about 10 ft. of wire. You never shorten that wire as they are originally calibrated to the lenght of wire that is hooked to them. You have to remember" Some one with only a lunch box invested built that arm" I am sure with some more information there is some way to repair it.
I don't know what is used on this machine but there are two basic load cell options, amplified and non-amplified. In either case two of the wires are sending power to the sensor and two are taking the signal back to the monitor. If the sensor is non-amplified the resistance could be almost anything but 350 ohm is pretty common. If it is made with a 350 ohm bridge, and they followed common load cell wiring practice, red/black and white/green will be 350 ohm, all others will be 262. If they used a different base resistance the lower pin readings should still be 75% of the other. The output signal will be very small, in the millivolt range. If the sensor is amplified the resistances will depend on the circuit used. Common output signals are 0-5vdc, 0-10vdc or 4-20ma. Compare the resistance readings between the two sensors, obviously they should be the same. If you get infinite ohms between all the pins the wires have likely been cut. ISZ