Originally Posted by dennis b
Not concerned right now about TV just trailer plug which is hooked up to good battery
If the TT is not on the ball, you do not have a ground. Hook the TT to the TV after confirming that you have power at the socket. Center post on the TV socket is the ground. Other ports are for tail lites, turn, marker lites and brakes. If no power thru the socket, you have a problem somewhere on the TV. If yes, see my previous post and check in the junction box.
Problem solving is a series of steps that isolate the problem. By learning what it is and what it isn't and by going step by step thru the system you will eventually find the fault.