Brakes on Horse Trailer Immediately Actuate When Trailer Is Plugged in to Vehicle

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Question:

I have a horse trailer that had brakes on it. It has been sitting and I have never used the brakes. I bought new brakes from you all the mechanical parts pre assembled and drums. Our truck was bought new with a brake box built in from factory leads me to believe that is not the problem. All the lights work correctly, however when you plug the trailer to the truck, brake on trailer lock up immediatly without applying brakes at all. The break away box bought from you is not installed yet? Any ideas? Thanks for your help.

asked by: Michelle S

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Expert Reply:

I am going to make a wild guess here. Your horse trailer has a 6-way trailer connector with the round pins, right? (most of them do). Your truck has a 7-way connector with the flat blade-type pins. In order to make them work together, you are using an 7-way to 6-way adapter, is that correct?

Here is where the problem comes in. There are two methods of wiring a 6-way connector. One method uses the center pin for the brake output voltage. The other method uses the center pin to carry the 12-volt circuit to power trailer mounted accessories. If the adapter is wired one way, and the connector on the trailer is wired the other way, the minute the trailer is plugged in to the vehicle, the brakes will apply.

To fix this, you can dis-assemble the adapter or the plug on the trailer and swap the wires for the 12-volt accessory circuit and the brake output circuit. Our wiring FAQ page that I have linked you to will show the interior wiring connections of a 6-way trailer plug. Once this is done, the brakes should work just fine for you.

If you are unable to take your trailer plug or adapter apart, we offer a universal adapter, part # 47549 that is easy to open up and swap the circuits.

expert reply by: Mike L

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Answer 1

There are two accepted ways of wiring a 6-way trailer connector. One uses the center pin as the 12-volt power accessory feed, the other uses the center pin for the brake output circuit. It sounds as if your trailer and adapter are wired differently,…

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Answer 2

I think I know what is happening here. Does the adapter you are using have 5 pins in a circle, plus one in the middle? This is a 6-way connector, there are two generally accepted ways of wiring this connector. One method uses the center pin as the…

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Answer 3

The reason your brakes are locking up when you use the 7 Pole to 6 Pole Adapter, #47549, is because there are two ways that 6-way round trailer connectors can be wired, as you may have already discovered. The difference is the pin for the electric…

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Answer 4

It sounds like you are using an adapter like the Hopkins #47549 to connect the 7-Way on your truck to the 6-Way on your trailer. You are on the right track with your troubleshooting as there are two common ways for a 6-Way connector to be wired; one…

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Answer 5

With 6-way trailer wiring there is two very common wiring pin-outs used and the only difference is that the 12 volt accessory circuit and the brake output circuits are swapped. Whenever we hear about 6-way wiring and brakes locking up the issue is…

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Answer 6

What you are looking for is called a #3015-S Brake Controller Wiring Adapter. The brake control wiring adapter is used to simplify the electric brake controller installation. The 4 wires on the adapter are butt-connected to the 4 wires coming out of…

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Answer 7

What you are experiencing is a common problem. Does the truck have a 7-Way connector and the trailer has a 6 way? If so, and you have used a 7 to 6-Way adapter to make the connection, the problem could be the adapter. There are two possible ways to…

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Answer 8

I have attached the common wire colors on a 7-way for you below but as not all trailer manufacturers use the same wire colors and they could have been replaced at one point in time so it would be best to test them with a 12 volt battery. Once you…

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Answer 9

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 10

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 11

Lance does have a proprietary plug, but many customers see a standard 6-way or 7-way round and notice it doesn't fit their factory 7-way as well. I've attached an article to help if you have one of the 7-way or 6-way round connectors which we…

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Answer 12

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Brakes on Horse Trailer Immediately Actuate When Trailer Is Plugged in to Vehicle

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