Trailer Brakes Lock Up when Connected to Truck with 6-Way Trailer Connector

Updated 06/25/2013 | Published 06/24/2013

Question:

We have a trailer brake plug on the trailer 6 blade with a center pin. The tow vehicle has a 6 blade with center pin receptacle. I dont know if the center pin on the plug is brake or hot, but the brakes are all brand new and they still lock up when we plug in. When I put the circuit tester in the center receptacle on the truck with the key on, there is no current, even if I push on the brakes. Shouldnt ther be constant power if its hot and power when I apply the brakes if its brakes? So Im now confused....I dont know how the center pin receptacle on the truck is wired, so I dont know if the plug on the trailer is backwards/opposite of the truck which is what I thought the problem was.. The truck also tows another trailer with a 6 blade with NO center pin, and the brakes work just fine on it. So, I have 2 queries... 1 why would the plug with no center pin work...why doesnt it need that pin ? And 2 what do I do next to make the trailer brakes work?

asked by: Barbara

Expert Reply:

This is a common problem with 6-Way trailer connectors. There are 2 ways that a 6-Way can be wired. The center pin will either by for trailer brakes or it will be the 12 volt circuit. On a vehicle side if you are looking at the pins center will either be hot or or brake output and the pin in the 10:00 position will be whichever the center pin is not, So if center is hot then 10:00 will be brake output.

All you will need to do is see where the corresponding pins on the trailer side connector end up by following the wiring back from the connector. Then you will just re-pin the trailer (because then it will match the other trailer) and you should be good to go.

Or you can use an adapter like # HM47570 because it sounds like the tow vehicle has a 7-Way blade connector. This adapter has a feature that allows you to switch between the 2 configurations of a 6-Way. All you would have to do is pull out the little tab on top, turn the tab 180 degrees and plug it back in to switch the hot lead and brake out put pins.

expert reply by: Michael H