I have a Cat D8T that is losing brake pressure when the priority valve turns on. The priority valve should be supplying additional oil for brakes and transmission control valves when turned on but I'm loosing 100 psi of brake pressure when it turns on. Has anyone ran into this before? If the machine is in first gear, it will power thru the brakes. But in second or third it will stop the machine just like you pressed the service brake. I checked torque converter pressures and all seem to be within range. Trans lubrication pressure is slightly low. Any help is appreciated. Thanks in advanced!!!
Found the problem. Ended up being low on transmission supply pressure because one of the bolts was gone on one of the modulating valves. All the pressure was going out the bolt hole. Currently trying to find the bolt in the transmission. Just figured I'd post an answer if anyone needs it.