Function of Blue Wire on 7-Way Round Trailer Connector

Question

Question:

Why do I need the blue wire on a 40 foot semi trailer? What does it control?

asked by: Doug B

0

Expert Reply:

Sounds like you are referencing the blue wire of the 7-way round connector like what's in the attached picture. If you have no use for an additional 12 volt circuit then it would not be needed. It isn't always needed so it sounds like you may not need it at all.

expert reply by: Jameson C

0

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Answer 1

The blue wire on a trailer is typically the output wire to the electric brake assemblies. If this is the case on your trailer then the wire should only have power when you are hooked up to the tow vehicle and are applying the brakes, either by…

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Answer 2

The easiest way to go from a 7-way round connector to a 7-way flat would be to get a Trailer Connector Adapter part #HM47425. However, if you are looking for a more permanent solution you would need to remove your 7-way round connector and wire up…

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Answer 3

The blue wire is for brake output power to the trailer brakes. One end connects to the brake controller and the other end goes to the pin in the trailer connector on the vehicle side that is for the trailer brakes. The Adapter 6 Pole to 7 Pole…

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Answer 4

You should get 12 volts coming from your brake controller if the controller is set on its highest setting. If your not, the first thing to do is to examine the trailer connector for any corrosion or debris and clean it if necessary. You'll also…

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Answer 5

To cover the easiest things first, make sure that the brake controller output or gain is turned up. If the power is low then the voltage on the blue wire will be low. When testing for voltage make sure to use the manual override and not the brake…

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Answer 6

I have added a photo detailing the wiring connections for the Pollack Heavy-Duty, 7-Pole, Round Pin conncetor, #PK11700, see link. This is a SAE J560 compliant connector. The wiring diagram for the vehicle side connector, #PK11720, is pictured also.…

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Answer 7

When wiring a 7-Way on your trailer with 5 wires, your green wire will be right turn/brake, the yellow wire will be left turn/brake, the brown wire will be the taillights, and the white wire will be the ground. You will want to find out if the blue…

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Answer 8

I might have an idea worth considering, but unfortunately I'm not aware of a product like what you are describing. It sounds like a cool idea though. I can't take full credit for this idea because I saw it on an overlanding blog, but he took…

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Answer 9

As long as the 7-way connector on your 2021 Volkswagen Atlas has 12v power the Autowbrake Electric Brake Controller - Trailer Mount - 1 to 3 Axles - Proportional #3430001 you were looking at will work just fine and is a great option as it installs on…

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Answer 10

Most likely the yellow wire on your trailer is what carries the reverse or auxiliary power circuit and would be connected to the center pin of the 7-Way like #PK12706. This would line up with standard 7-Way wiring for a 5th wheel or travel trailer. I…

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Answer 11

No, on an electric drum brake assembly the magnet wires are NOT polarized so either wire can be attached to the frame as ground or used for the +12V brake circuit. Do your best to make sure the ground wire is attached to a rust-free, grease-free bare…

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Answer 12

You likely can use any replacement switch since all they do is complete a circuit when the pin is pulled out. One wire on the switch should be connected to the positive battery terminal on the trailer. The other will tee into the wiring leading from…

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Function of Blue Wire on 7-Way Round Trailer Connector

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