Electric Trailer Brakes Won't Release After I Hit Brakes


I just bought this trailer 9 ton 3 axles. It had a 5 pin plug I changed it to a four pin left out a blue wire.i thought was the electric brakes. I drive down the road and the electric brakes ingauge when I apply my brake in the truck and wont release. I cut the red power wire off the plug and the brakes released. Is this blue wire to release the brakes? Or do I just need a 7 pin to correct this.


Expert Reply:

On a 5-way connection, the blue wire is normally for the brake controller as you stated. However the color of the wire in this case probably won't help us as it is evident this connection has already been tampered with. I have attached a trailer wiring diagram for you. The focus should be on the function of the wire and not on the color of the wire, so we can pair the correct functions at the trailer and vehicle connection points.

To test the trailer wires, you can get a 12 volt batter with two leads connected. On to positive and one to negative on the battery. Connect the negative lead to the trailer ground and then use the positive lead to figure out the light function of each wire. Power to the brakes should activate the brakes and release when removed from power.

I recommend with that big a trailer that you use trailer brakes, and would upgrade to a 7-way connector. I recommend using the Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat, # ETBC7. This kit will allow you to connect your 4 way flat from your tow vehicle into the connector and then you connect the reverse wire if desired and run the power and brake controller wire. This kit includes everything you need from wire, to connectors, to circuit breakers. I have attached the instructions as well as an installation video for you.

You can use any brake controller with this system, but I recommend the Tekonsha Prodigy P3, # 90195. This controller is an easy to read option with an LCD screen. It gives three different boost options and runs constant diagnostics without the hassle of deciphering codes.

For the trailer, I recommend the Epicord 7-Way Molded Trailer Plug with Junction Box - 10' Long, # 277-000141. This will allow you to convert your current trailer brakes into a 7-way connection with easy connection points that make any future issues easy to identify.

expert reply by:
Jason S

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