philh wrote:
Pull the brake cable on the trailer. That should lock up each wheel.
This is the way I check my enclosed trailer brakes.
Checking the integrated controller and connection is a little tougher since it uses technology that defeats the old methods. You may be able to squeeze the controller paddle to verify signal is coming on the brake wire, but it may not output anything without a trailer connected and only limited voltage when not moving. Once you know that your trailer brakes actually work by pulling the pin, the best way to check the controller is to squeeze the paddle while driving at 30+ mph.