Trailer Brakes Lock Up When Using 6 to 7-Way Trailer Connector Adapter

Updated 10/10/2018 | Published 10/09/2018

Question:

Got a 99 Dodge Ram with factory 7 way recepticle and a horse trailer with 6 Pin round plug . Bought an adapter and the brakes lock up when I plug the trailer in. Have tried switching the wires on the center pin and brake pin. I have a blue, brown, black, red, green and yellow wires on the trailer plug. Put a continuity tester on the red and black wire and it shows it is grounded to the trailer could this be my problem?

asked by: Don

Expert Reply:

It sounds like you have a wiring mixup either on the vehicle or trailer. In order to check this you are going to want to test the vehicle with a circuit tester and the trailer with a 12 volt battery. You can then use the two photos I have attached for you to make sure the wires are in the correct terminals on the trailer connectors. I would also check with the manufacturer of the 6 to 7-way adapter to see how it is wired. For example, the Adapter 7-Pole to 6-Pole part # 47549 is wired so that the center pin is for the hot lead.

If you have checked the wiring of the trailer connectors and adapter, then the only other thing to do is begin checking the wires on both the trailer and vehicle for shorts as the blue brake output wire and black 12 volt power wire could be shorting out to one another which is then causing the brakes to lock up when the trailer is connected.

expert reply by: Conner L