• If you use a trailer brake controller with your trailer, the trailer brakes may be activated and deactivated with the brake switch. If so, there may not be enough brake pressure to hold both the vehicle and the trailer on a hill when the brake pedal is released. Install trailer wiring 2012 jeep liberty 55027 - etrailer.com - Duration: 4:04. Install brake controller 2013 jeep wrangler 90885.