Abstract: A trailer break-away switch comprises an electromechanical means to energize a towed trailer brake in the event of unintended decoupling of the trailer from the towing vehicle. When in normal operation, the trailer break-away switch operates as a normally open switch between the stored energy source (the battery) on the trailer and the trailer brake system. In the event of unintended decoupling of the trailer from the towing vehicle, a pin is pulled from the trailer break-away switch, which activates the switch. Activating the switch allows electrical power to be connected to the trailer brake system. In some cases, the switch directly connects a trailer battery to the electromagnetic coils of the electric brakes.