JD CT322 breaks slowly setting

[OldAllis]

I've got a CT322 with a break problem. The breaks will not release until you raise and lower the boom a couple times and then it is good for a bit. This works while the machine is cool, as it warms up the breaks will gradually get tighter until they lock up. Once the machine cools off a little you can then get it to move again until it heats back up. The engine temp seemed to be getting a little hotter than normal but not sure because the breaks lock up at this point. The seat and seat belt switches checked out. We replaced the park break solenoid and it didn't help. It seems like there may be too much pressure in the hydrolic system. It is also putting out these codes-F9H9, F9P8, F9P9 not sure what they mean. Deere has been no help. Any suggestion would be greatly appreciated. Thanks

 

[OldAllis]

I have now eliminated it being a wiring problem by running though the park brake circuit which checked out and then manually controlling the park brake solenoid. I have moved on to the hydraulic system now. To me it seems like something is either clogged or malfunctioning not letting the fluid pressure to properly release untill you raise and lower to boom. Or something is letting pressure in when it shouldn't be. The park brake solenoid is mounted in the edge of a flat box. I was wondering if this box could be the problem? Or if there are other components in the system that should be checked? Is there another way to check hydraulic pressure than where the book says? I'll have to get the fittings to check system pressure. This machine was missing the port for whatever reason. This is a 2007 JD CT-322