Electrical brake wiring system diagrams are available at etrailer.com, AccessConnect.com and EasternMarine.com, as of 2016. Additional sources for brake wiring diagrams include CarMate-Trailers.com and BlackMilkMedia.com.
Etrailer.com features a brake controller installation guide that includes systematic installation instructions, a wiring diagram and actual photos of the wires and connections. The diagram illustrates the routes of the 12-volt blue, black, red and white wires, as well as circuit breakers and connector components. Etrailer also sells automotive towing parts and accessories.
AccessConnect.com is an automotive parts and accessories retail website that provides a free trailer brake controller installation guide, as well as multiple free trailer wiring diagrams. The website's brake controller installation diagram illustrates wire routing and connections for electric brakes, reverse lights, power switches and grounds.
EasternMarine.com is a trailer parts and accessories retail website that features a vehicle brake control wiring diagram for 12-volt electric brake control systems. The diagram includes visual representations of components and connections, wire descriptions and important safety tips and instructions.
Car Mate Trailers is a manufacturer of custom open and enclosed trailers. The manufacturer's website features a 12-volt seven-way trailer-wiring diagram that illustrates wire routing to and from the charger, breakaway switch, brake controller and other components. Diagram features also include pictures of car and trailer connection ends and plugs.