Trailer Mode alone does not always work; the Model X won't activate its trailer light circuit unless it sees enough current draw on certain circuits - which doesn't happen with some trailers such as the Airstream Bambi and the Bowlus Road Chief, both of which have Prodigy brake controllers and LED taillights. An easy fix is to draw at least 10 milliamps on all six trailer circuits, which can be done either by purchasing an LED tester and wiring it in parallel with the brake controller's connector head, or by somehow putting 1200 ohm resistors across all six trailer circuits, which draws less than a Watt of power.
