I am working through an electical problem with my trailer brakes.

When I hookup the battery for the brakeaway, with the brakeway switch open (plug inserted), I get sparks from the wire I am connecting to the battery, the trailer brakes kick on, and my brake controller in the tow vehicle displays the light that indicates a wiring problem.

I last used the trailer in early May, and each time I use the trailer I check the breakaway system to ensure it works (it did in May). The other week (without testing the system) I put the breakaway battery on a battery charger overnight without disconnecting the trailer wiring to the battery, but I did leave the breakaway switch plug inserted, which I would think disconnected the battery from the trailer wiring.

When I hooked up the trailer to the tow vehicle and pulled the plug on the breakaway switch, my brake controller started smoking and fried itself.

After running over to Walmart and purchasing a new brake controller (one with a light that will light up when it senses a wiring short, and has built-in short protection) and a new battery (small lawn mower battery) and installing all the new parts, the trailer brakes act the same, they kick on as soon as I connect the new battery, and now the brake controller displays the light that indicates a wiring short.

I cut one of the wires to the breakaway switch, same thing, brakes kick on and wiring short light is on.

With the breakaway battery disconnected, the trailer brakes work fine with the brake controller.

Any ideas on where the problem may be? Could it be a bad brake magnet?

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Todd Cohen
ITB Nissan 200SX