4-Way Trailer Connector that has 5 Wires

Question

Question:

The dog chewed up the flat connector on my trailer which has five wires, white, green, yellow, brown, and black. I bought a four wire flat connector at Autozone, for the trailer, but only offers a four wire connection. Do you run two of the five wires into one connection position, and if so, which ones? Or, does the black wire even need to be connected?

asked by: David F

1

Helpful Expert Reply:

Did you have a 4-pin connector that had 5 wires or was it a 5-pin connector? There is a big difference since you normally see a 5-pin connector on a boat trailer with the 5th pin used for an electric reverse lockout solenoid on a brake actuating coupler. If it was a 4-pin connector with 5 wires then it is called a wishbone harness and would have 2 wires attached to the running light pin so you have one wire for each side of the trailer.

Typically, on a 4-Way, the white wire is ground, brown is running lights, yellow is left turn/brake lights, and green is right turn and brake lights. A 5-Way will have the same functions but then usually a blue wire at the end for that electric reverse lockout I mentioned.

On a wishbone 4-Way you would have a ground wire and then you usually see a brown wire with yellow stripe for the left side running lights and a brown wire with green stripe for the right side running lights. They are attached to the same pin. All of the other functions are the same.

expert reply by: Michael H

1

Marshall

2/29/2020

Well from the original question, what do you attach the black wire to?

Reply

Chris R.

3/2/2020

This depends on if it's a 5-way connector or actually a 4-Way connector with 5 wires. Just going by the process of elimination, if it's a 4-Way the black wire would be one of the running lights circuits along with the brown. If it's a 5-Way I have to assume it would be the reverse circuit wire. If you can tell which pin/terminal on the connector the wire's actually leading to, I could hopefully give you a more certain answer.

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Dennis B.

2/25/2024

@ChrisR I have 4 pin 5 wire Trailer brake has a black and white. Where does the black tie into?

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Mike L.

2/27/2024

@DennisB A 4-pin connector won't have the provision for trailer brakes. What braking system does your trailer use? Electric, or do you have a surge coupler that compresses when the tow vehicle brakes which hydraulically actuates the brakes?

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See All (7) Replies to Marshall ∨

Mark C.

5/10/2020

I have a 5 wire to 4 flat , I put the green to green, yellow to yellow and the 2 brown with stripes to the the running light pin and white to white, I have no brake lights and no right turn?

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Chris R.

5/13/2020

From where I'm sitting you seemed to have wired everything up correctly (unless your trailer uses odd wire colors). I might take a circuit tester to the 4-Way on your tow vehicle just to make sure you're even getting appropriate power there - the issue might be on that side. Test the pins while you have each light function activated to ensure you're getting power from the vehicle - if not, check for blown or missing fuses under the hood, frayed wiring on the harness, etc. If the vehicle checks out, make sure the light assemblies are still securely grounded and inspect any wiring you can access for damage. Let me know what you find and we'll keep going if needed!

Reply

Dennis A.

11/16/2021

I have a 4pin flat hooked to a wishbone 5 wire flat. Dim running lights . Could it be that the trailer is grounded through the ball when hooked up . Could that be a double ground?

Reply

Les D.

11/23/2021

Behind the bumper, the truck has a white wire coming off the back of the connector receptacle. That white wire grounds to the truck nearby the truck receptacle. The white wire that goes to the trailer also connects to a conductive part of the trailer. The trailer could ground through the ball, but it is more reliably done through the ground wires. Remove the screws grounding to the truck and trailer. file the connection point to shiny metal, and file the connector ring clean as well. Poor grounding is most likely the cause of your dim lights. If you happen to have a second truck around you could hook up the trailer to determine if the problem is on the truck side or trailer side. Let us know if you need further troubleshooting.

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Answer 1

Going by the colors that you mentioned, it sounds like you have the typical set-up, green wire for right turn and brake, white wire for ground, yellow wire for left turn and brake, brown with green wire for right side running lights, and brown with…

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Answer 2

Your 4-pin/5-wire wiring harness is what is called a "wishbone" type which simply means that there are two separate running light wires, one brown and one pink. This allows a separate running light wire for each side of the trailer which…

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Answer 3

It would seem that your tow vehicle has a typical 4 wire connector where white is ground, green is the right turn signal, yellow is left turn signal and brown is running lights. In this configuration the brown wire from the car connects to the brown…

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Answer 4

You will still be able to use the trailer with the 4-Way after installing the 4 to 5-Way adapter, #20036. First, you could just remove the adapter if you wanted to and then plug in the 4-Way like normal while stowing the adapter in the truck. The…

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Answer 5

It sounds like you have a wishbone wiring harness install on your trailer. A regular 4-way wiring harness has 4 wires from the back of the connector, 1 for left turn/brake typically (yellow), 1 for the right turn/brake typically (green), 1 for the…

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Answer 6

Some 5-Pole flat connectors use a total of 6 wires. They operate as follows: Blue - trailer brakes Green - right hand brake and turn signals Yellow - left hand brake and turn signals Brown/Green - right hand running lights Brown/Yellow - left hand…

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Answer 7

On a 4-Way flat trailer wiring harness, white is the ground, brown is running lights, yellow is left turn signal and green is right turn signal. It sounds like your trailer has a wishbone harness. A wishbone harness splits the running light circuit…

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Answer 8

There are differences in them but we do have what you are looking for and they can in some situations be used together. The Replacement Trailer Hub Bearing you have part #02475 and Replacement Race for 02475 Bearing part #02420 are designed to work…

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Answer 9

On your trailer you originally had what is called a wishbone harness. This type of harness has the running light circuit split at the connector so one wire will run to the left side, the other to the right side. This is so you do not have to have a…

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Answer 10

Hey Tom so I definitely know what you are asking for but due to the very minimalistic design of the Kuat Transfer part #KU84FR there isn't a great way to add lights to it. But the good news is that you most likely don't need additional…

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Answer 11

Actually, both of your friends are correct about the Thule Hitching Post Pro Bike Rack #TH934XTR. This great Thule rack will fit BOTH 1-1/4-inch and 2-inch trailer hitches thanks to its included adapter. Do note that some 1-1/4-inch hitches are rated…

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Answer 12

Behind the dash to the left of the steering column there is a socket for a blue relay like the one included in the Curt Relay Kit #C57000, to install that controls the running lights circuit. See attached picture for more info on this.

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4-Way Trailer Connector that has 5 Wires

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