Electrical problem

We just brought our beautiful 2007 264SR
Home from its winter nap. Put a brand new battery and also plugged into shore power 15 amp outside plug at the house been doing this for many years.
Well today it kept tripping the ground fault on that outside plug. Thinking maybe it’s the plug I plugged it into another outside plug on an entirely different circuit and lo and behold it tripped that ground fault also. Looking for a little guidance any suggestions on where I can look and see what’s causing this problem.

Thank you Laird