Hello, I am working on my Bobcat 753 F Serial number 515 815 700, with trim tilt pedals. It was working great and all of a sudden I had no trim and tilt. So far I have done the following: Checked power at the BICS connector, 13.5 Volts Replaced the BICS Coil. Checked the BICS valve for actuation with 12v at the connector. I get a loud click indicating its working. Removed and cleaned the BICS valve. All of the auxiliary's still work great Fluid level is full. No flashing lights on BICS display, all four green and solid. When it quit working the arm was mid lift and I was able to use the pressure release valve to lower the lift arm When I depress the pedals I can see the hoses shift/wiggle, indicating that they are receiving pressure. But how much? I tried tricking it by lifting the pressure release valve and that didnt work. Any thoughts on where to troubleshoot next? Thanks for your insight and suggestions.
I forgot a couple of details. The BICS coil had approximately 10 ohms resistance. All of the oil and filters are fresh and have about two hours of use. A few years ago I rebuilt the trim tilt spools as they were leaking but I did not touch any other parts in the assembly. My latest thought is to purchase a hydraulic line pressure test kit. I hope to be able to verify the pressures and pinpoint what part of the assembly is not working. I have the OEM service manual on its way, but I do not know how to read a hydraulic flow chart or where to begin. Any suggestions?
still troubleshooting this. I thougt it was a bad relief valve, I ordered a new oem one and I am still having the problem. Installed a new BICS valve and coil, still having the problem. Resealed the directional control valves, still having the problem. Any suggestions?
Thought I would post a follow up in case anybody ever needs the info. Everything started working!! Here is would did it: 1. I had done all of the above items that I mentioned in the previous posts. 2. I suspected that one of the relief valves were stuck open or closed in the hydraulic block. So i kept raised the rear up with my stabalizers and kept tilting the bucket back and forth. Eventually something changed and the lift and tilt started working. This took about 20 minutes. My best guess as to the problem. during summer I did all of my preventative maintenance and everything worked great. I used the machine for tow or three hours once it was finished. My local temps during that time were up in the 80-90 degrees and I installed some "universal heavy dusty tractor and hydraulic oil" that I found at my local store. It worked well. I suspect that the bobcat didnt like it when the temps dropped down in the 50's and 60's and the thicker oil allowed one of the worn relief valves (5400 hours) to stick open or closed. My guess is that when I kept activating the trim and tilt for a extended period of time it allowed some of the hotter oil in hydraulic block assembly which allowed the valve to unstick. THIS IS ONLY MY BEST GUESS. So I drained all of the oil and installed the bobcat hydrostatic fluid. I hope this keeps the problem solved. If it doesnt I plan on taking out the hydraulic block and simply replacing all of the relief valves and seals.
Follow up to the follow up. It wasn't the oil. It turns out the bics valve was getting intermittent voltage. One of the pins at the multi pronged connector was extremely loose.
Thanks for the info. It will be very helpful to the next guy. I had a learning exp with the bics on a T550, just a bad coil.
I wouldn't have thought it would be an oil problem. Maybe contamination in a valve or something. I'm very glad my skid steer has no electronics and is pretty basic.