Where To Attach Blue Wire From 5 Wires on Trailer When Installing a 7-Way Connector

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Question:

I have 5 wires from trailer to a 7 way blade. Where does the blue wire go?

asked by: Scott

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Expert Reply:

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 wire on your trailer is needed for 12-volt power for trailer accessories, for electric brakes, or for a reverse brake lockout, if your trailer has surge/hydraulic brakes.

Looking at the rear of the 7-Way connector, if you need the blue wire for electric brakes it would attach to the # 2 terminal at the 5 o'clock position. If you need it for 12-volt power, you will attach it to the # 4 terminal at the 1 o'clock position.

If you need the blue wire for reverse brake lockout you will attach it to the center pin of the 7-Way connector. You might want to test the center pin on the 7-Way, with a circuit tester, like part # PTW2993, on your vehicle to make sure it is wired for reverse lights.

The additional blue wire is tapped into the reverse lights on the vehicle to disengage the hydraulic trailer coupler (actuator) when the vehicle is reversing, thus turning off the trailer's brakes.

I am including a picture of a 7-Way trailer connector that will show the terminals and their function. Also, I am including a link to a FAQ page on trailer wiring.

expert reply by: Jeff D

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Ronnie L.

1/28/2020

where do i attach the blue wire from 5 wire on my trailer when plugging it into a 5 to a 4 adapter on my bike . The trailer has no brakes but it does have 3 lights on the back that don’t work when it’s plugged up but all the other lights do . Is it possible to tie the blue wire in with the brown .

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Jacob H.

1/29/2020

On a lot of motorcycle trailers the brake signal and the turn signals are on three separate wires which is where you are getting the extra wire from. By using # RM-732, you can split the signals from your bike so that the trailer is getting the proper lighting functions.

Helpful Links

Wiring/Roadmaster/RM-732.html

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Brian A.

3/21/2020

I have a five 5 wire trailer connected into a seven pin plug. My colours are Blue, yellow, Brown, white and black. Which wires are wired to which in the seven 7 pin plug configuration.

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Chris R.

3/22/2020

Your wire colors don't quite match up to the typical trailer configuration (going by standard color functions you would be missing a wire), so your best bet here is honestly to test each one for function. Apply 12V to the wires to see what each activates on the trailer. The white is most likely your ground wire.

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Brad B.

4/17/2020

My truck only has a light blue wire for CHMSL no dark blue for trailer brakes.Got a curt Echo, my 7 pin connection has a dark blue and red wire left to hook up somewhere and I only have on my truck1 light blue wire left. Help! Please!

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Chris R.

4/18/2020

If you're using the Curt Echo you actually don't need the blue brake output wire. The Echo only requires the 12V circuit (in addition to the turn signal circuits) for proper operation. You can just cap that blue wire off. The factory wire color functions might be listed in the truck's owner's manual, but if not, you're best route will be to actually test that remaining wire with a circuit tester. See which function on the truck sends power to that wire to determine its purpose (and in turn where to connect it on the 7-Way). Let me know what you find and we can go from there.

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Charles S.

6/4/2020

What if the center pin not working in reverse what then

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Chris R.

6/8/2020

I would try to check the wiring at the back of the connector to make sure the reverse circuit wire is still secured to the truck's wiring. Is this a new connector? was it hardwired?

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Steve M.

7/13/2020

I have a 2014 Ford Edge and need to install a 5 flat connector to the vehicle. I can't determine which wire to tie into. There is a large plug connection under the rear end and three pins had continuity to the back up light but neither worked as it should.

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Chris R.

7/17/2020

You'll want to try and tap into an actual wire - can you trace that plug a little further up the Edge?

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Answer 1

The best solution for your situation would be to use a circuit tester, like part #PTW2993, to wire your trailer wires to a seven-way trailer connector, like part #A7WCB. Wiring by function is the best way to make sure you have the trailer connector…

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Answer 2

I've linked a help article that will give you the common color coding but on your trailer I wouldn't go by it. Even if they are correct you just never know so I suggest testing it. To test it cut off the 5-way connector that's on there…

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Answer 3

I've attached a diagram for you with function locations. Your left turn and stop are what will need to be connected for the flashers to work. These are found on the left and right side blades of your 7-way connectors. I recommend using a circuit…

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Answer 4

Since wire color codes are NOT universal, we always recommend wiring by function, rather than wire color. If you look at the Trailer Wiring FAQ article I have linked you to, you can see some diagrams showing the proper way to wire a vehicle and…

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Answer 5

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Answer 6

A 6-way round-pin trailer plug like Pollak #PK11604 has a center pin that can be wired in two ways. The most common function to be found on that center pin is 12V trailer power. This is a low-level maintenance charge that will maintain a charged…

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Where To Attach Blue Wire From 5 Wires on Trailer When Installing a 7-Way Connector

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