You are definately sending 12V to your trailer brakes. You lost me on what plug you converted to. Can you post pics.

It is possible that it's the fault of the brake controller. Check the blue wire at the brake controller for power with the trailer connected. If it reads 12V then you have a bad controller. The voyager is inertia activated so if it's mounted vertical and you have 12V to the red (signal) wire then it will do the same thing.

What I think is going on is you have the 12V wire hooked to the trailer brake circuit on the trailer.