Hi Wondering if anyone has experienced the same issue i am having and if you were able to get it fixed? SV300 UCM delivers lower current to left hand forward solenoid coil than the right hand forward solenoid coil causing the machine to turn left at crawling speed, if I switch the wiring plug from the left forward to right forward coils the machine turns right in ISO, the dealer has swapped out the UCM and made no difference, installed new joystick pods and made no difference, the service supervisor recommended changing the cabin and chassis wiring looms, talking to the mechanic that worked on my machine over a couple of months and he recommended replacing the pump and wheel motor so no continuity there. as many of you know Bobcat has drift compensating software to combat drift but Case does not, I have hot wired the loom from the UCM to the Pump and made no difference, I am wondering if anyone knows if there is any such thing as a digital or automatic potentiometer or transformer (important to remember I know nothing about electronics) the difference between the current delivered to the two coils is the same percentage wise from 0 to whatever the maximum current delivered so thought if I could get something to either increase the current to the left coil or decrease the current to the right hand coil I could address the drift, the dealer has re-calibrated the ucm a hundred times with no improvement, the issue began when the operator got a right hand swash plate sensor fail code intermittently over a few nights then we delivered it to the dealer who replaced the swash plate sensor then installed the wrong software requiring several return visits, the issue of the was not noticeable prior to the swash plate sensor being replaced. would appreciate your help?
Update see video on youtube It shows what is happening the dealer says nothing can be done
If the resistance on the coils is different they will draw proportionately different levels of current
Thanks for the reply Mike I have swapped the coils around and makes no difference, have hot wired the wiring loom from the UCM to the coil still no change
Is it a closed loop system... speed or pressure sensor somewhere.... it's trying to compensate for something
Case Skid Steers dont have speed sensors on them and no software for drift compensation unlike Bobcat, yes its a closed loop, not sure if its compensating for anything the dealer has given up trying to look for the problem and i have had it to a Rexroth specialist who has told me its not the pump or the motor causing it.
Sorry, I meant electrically a closed loop... as in is there feedback from somewhere
Sorry did i mention that my specialty is operating skid steer machines lol from the UCM to the pump there are two wires to each coil an earth and the active, there are six wires going to each swash plate sensor, two earth wires and two of the wires go back to the UCM to tell it where the swash plate is and the other two I think are to tell the system that something is not working.
So what is the controller reading for swash plate voltage... reading at the controller
by controller do you mean the UCM or the joystick? this is where i get lost I will upload a pick of tests run by the rexroth man, the schematics in the manual i have dosen't read the drawings making it impossible for me to track where the wires from the swash plate sensor go. I am assuming the dealer would have checked the swash plate output voltage but you never know, I dont know how the sensor interacts with the coil amperage I did check the resistance of the swash plate sensors against each other and couldn't identify a problem.
Well you inputs to the controller would be Joystick and swash plate angle.... output would be proportional coils on the pump If the controller is reading identical swash plate angle voltage that would be your problem.... bad connection... wire... sensor