Hydraulic trailer brake problem

I pulled a wildcat 5th wheel home for a friend...3/4 of the way home I noticed my factory controller was putting out a "trailer disconnected" error...had the green trailer displayed(everything's ok) when we started our trip. So we stopped at a rest area to make sure brake lights & turn signals were at least still working...they were. Went on to her house & dropped the trailer off.

Moved my 5th wheel last week & noticed that my electric over hydraulic brakes that are on my trailer are now surging...as in...step on the trucks brake pedal & no immediate assistance from the trailer brakes...after a couple of seconds of nothing...then I get a surge of too much brakes from the trailer...enough to move you forward in your seat a little bit when it happens...

Think maybe the Wildcat trip blew a fuse somewhere in line & it's now affecting the workings of my system? Mine is the factory controller in a 2008 Ford 250.

Any ideas of what to look for, when I tear into things?