Horse Trailer Brakes Immediately Apply Once Trailer Is Plugged In  

Question:

Expert Reply:

I am guessing both horse trailers use a 6-way trailer connector, and you are maybe using a 6 to 7-way adapter, correct?

There are two accepted ways of wiring a 6-way trailer connector. One uses the center pin as the 12-volt output from the brake controller, the other use the center pin as the 12-volt accessory feed. If the trailer connector on the vehicle and the connector on the trailer or the adapter are not wired similarly, the trailer brakes will engage as soon as the trailer is plugged in, which is what you currently have happening.

Take a look at the trailer connector used on your 2 horse trailer. Can you dis-assemble it in order to access the terminals at the rear of the connector where the wires attach? If so you can, swap the wire on the middle terminal and the wire on the terminal labeled (S).

If the wire is NOT accessible, you can use an adapter like # 47549. You can open the adapter and swap the brake output and 12-volt accessory circuit as needed. You can place some colored tape on that adapter or mark it in some way so that it is always used with that particular trailer.

expert reply by: Mike L

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