I have a nice Komatsu PC75UU series 2 that is showing a 51 code that I think is a bad boom position resisters. This is a grey machine and the Komatsu dealer told me “We don’t work on that ****” and I can’t find anyone that knows how to fix it. Anyone know how to fix it or convert it over to straight hydraulic and eliminate all the Electric crap? I only use it on my farm and don’t need the boom position sensor
I don't recall those machines having provision for diagnostic codes. I have a PC78UU manual and it doesn't mention any of that. Maybe your machine is a later model. Can you take a photo of the monitor panel in the cab and the computer that should be mounted somewhere behind the cab so we can identify what you have. What you are calling resisters are actually potentiometers. They can be checked with an ohm meter. The linkages can get bent or damaged is one common problem. The other is the wiring and harness connectors.