Not being familiar with that machine, I'm just guessing here, but since there are no other problems showing up, that would preclude a pump issue.
I'm betting that the 4 way plugs into the aux hydraulic circuit, check any electrical connections related to that. Most times they will look fine, but have a bit of internal corrosion that changes the signal that the controller is looking for. Sometimes just unplugging and reconnecting them will clean them enough, I'd give them a shot of contact cleaner for good measure.
That's an easy and cheap first step; if it still does the same thing afterward, it could be the aux solenoid controller, Tazza has worked on them and will have some good tips for dealing with them.