How to Wire a Trailer Breakaway System on a Trailer

Published 01/21/2009

Question:

On the breakaway diagram without charger, there are three wires coming off the battery. Does the positive lead from the battery connect to the aux power from the tow vehicle and through the breakaway switch to the electric brake feed? In the event of a break away, a full 12 volt signal goes to the breaks. Otherwise, on a limit voltage potential is sent to the breaks from the break transmitter box in the tow vehicle?

asked by: Joe

Expert Reply:

Check out the wiring diagram I attached, I think that will make more sense for you. There are 3 wires coming off of the breakaway battery as you indicated. The black wire will tie into the 12 volt hot lead from the trailer connector. This will provide a trickle charge to the breakaway battery while you are towing.

The white wire should be grounded to the main trailer ground and the blue wire will connect to one of the leads from the breakaway switch. This wire will send power to the trailer's brakes in a breakaway situation.

The other lead from the breakaway switch will tie into the electric brake wire on the trailer. This is the wire going from the trailer connector to the trailer brakes. The pin in the breakaway switch prevents power from the breakaway battery from reaching the electric trailer brakes.

expert reply by: Mike L