is something wrong or is it normal for the factory trailer harness to have 12 volt output independent of the light switch or ignition? The brown lead is has a constant 12 volts to it even with the lights off and ignition off. Hence my trailer lights stay on when parked unless i disconnect the harness.

No that can't be right, I have an aftermarket setup but it should act just like the lights on the car itself. If no car lights are on, then there should be no trailer lights. It it the running lights or brake light that stay on? The reason I ask is that the brake light circuts always have power, that's why you can push the pedal an the brake lights work when all else is switched off.

:wave: it depends what type of plug you have. if it is a flat 4 no there should not be any power unless lights are on. a flat 4 is like this yellow is right trun/brake, green is left turn/brake, brown is park, white is ground. if it is a 7 pin there will be a red + from batt(will have power all the time), black - batt, blue trailer brake. If you still have trouble any RV dealer will be able to help you:burnout: