Brake lights working but Prodigy says not connected

I am pretty sure the wiring on my trailer or the umbilical cord is not standard. I guess I will be re-testing all the wires on the cord to make sure they are accurate.

Is there a best practice for doing this. I expect it will be easy to find the rt and lft blinkers, reverse, and clearance lights, but not necessarily the ground, electric brakes, and Aux power.