Ive got a later 544H we just bought off of an auction and we have 3 issues with it. The main issue is the Boom will intermittently not raise when pulling back on joystick. Ive T'd in pressure gauge into pilot hose for boom raise and it is in spec and every time i go to boom up it pressurizes. I've put a gauge on the test port for pump pressure and its not going into stroke when i go to boom up. When we first got machine probably 50% of the time it would not boom up when commanded and now its down to probably 20% of the time and has gotten better. To get it to boom up you can either pull back on joystick for extended period of time and it will raise or you can use one of the bucket functions and everytime it will start to boom up and when you let off the bucket functions sometimes it will continue to boom up and sometimes it will just stop. The times when it will not boom up it does not sound like the engine is straining its just like the joystick is in neutral. When the pump goes into stroke it builds right around 4600PSI and all functions are strong and quick when they do work. I do have access to JD service advisor and have done almost every pressure test and they all seem to be in spec. I also pulled the boom raise spool and it slides smoothy in the bore and there no signs of rust or sticking. The second issue im sure is related to the first and that is that the steering is slow and jerky and when it is slow and jerky the pump is not going into stroke same as the slow boom lift issue if you use a bucket functions or mash the brake quick it will steer fast and smooth when pump is in stroke. The third issue is when you put it in forward it will try to go into 4th and seems like it slips for a few seconds then downshifts into 1st and drives fine, then you can shift to 2nd and it goes fine but then it will not let you shift to 3rd or 4th and just stays in 2nd. reverse trys to start out in 3rd then goes to first and all you have is 1st and 2nd reverse. It is throwing no codes and and there are no lights on the dash. I read in another thread that if the ZF transmissions have a bad speed sensor they will default to 1st and 2nd gear but i would think it would throw a code. Any help is greatly appreciated. We've been able to get along loading dirt with it alright by messing with bucket functions to get it to boom up. But when trying to load equipment with pallet forks it is a huge nuisance and borderline dangerous not being able to get the boom to raise when you need to. Since its gotten better im thinking a spool sticking and its needing more pressure/flow to get the pump to go into stroke.
Most likely a bad output shaft speed sensor on the transmission. I just had one with this exact complaint and that was the issue. On the H, you can view the speed sensor outputs to verify it is an issue. If you have the Operation and Test manual, then in the electrical section it will tell you how to get to the sensor readings in the dash. Most likely a load-sense shuttle check issue. Did you check the load-sense pressure? Below is where the load-sense check can be found. There is one for each work section. As far as the steering, the shuttle check in the outlet section could be an issue. Again, the hydraulic theory section on load sense will show where these items are located.