Electric Brakes. How do these work?

Electric brakes work like any other type brakes, only use 12-volt electric to actuate them. There are two heavy wires that run to the axle and basically split between both sides. It is just simply + and - sides. These are controlled b the tow vehicle, through an electric brake controller, and plugged through the (usually) 7-prong trailer plug. Most modern trucks and especially those that boast towing packages, are prewired for electric trailer brakes, although most still require an aftermarket controller.   The controller puts voltage to the brakes, stopping the trailer without wearing the pads off your tow vehicle.

Here are some brakes....



In my particular case I found that the connections were shorted out, likely in the magnet setup in the brakes.  I changed the whole units, as well as the wiring to the plug.  You can kinda test brakes with a 12-v battery...I use the battery out of my lawn mower.  Touching the wires to opposite posts should produce a click or tapping noise in the hubs.  If nothing happens then they are likely frozen up.  Hot sparks at the posts will indicate a short.

P.S.  Your running lights should most likely although not always be a green wire in the trailer plug....about 14-ga.