How to Determine Trailer Wiring Color Functions

Question

Question:

Ive attempted to connect new lights to my boat trailer. Im confused by the wiring that runs from the lights having only four wires - red, blue, white and brown. Im trying to attach it to a small 7-pin round plug that obviously has yellow and green for left and right blinkers. What do I do?

asked by: Clint H

0

Expert Reply:

Since wire colors on trailer wiring aren't standardized you will need to test the wires on your trailer to determine their function before you can wire them to a trailer.

An easy way to do this is to use a 12 volt battery and a jumper wire to apply voltage to each wire to see then what circuits activate. I attached a picture that shows a wiring diagram of a 7-way for you to check out as well.

expert reply by: Jameson C

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Answer 1

The three most common lug stud sizes for a trailer are 1/2"-20, 9/16"-18, and 5/8"-18. In order to make sure you get the correct lug nuts you need to measure the lug studs on the trailer now as we have no way to look this up for…

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Answer 2

You have a wishbone harness like #A20WB. This type of wiring harness splits the running light circuit at the trailer connector, so you don't have to run a jumper wire from taillight to taillight. The yellow/brown wire is the running light circuit…

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Answer 3

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…

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Answer 4

I am a little confused as to were the connector is, on the truck or on the trailer. Brown wires are typically associated with running lights. If there are 2 wires coming out of that pin and we are talking about the trailer side then you have what is…

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Answer 5

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 6

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 7

Trailer wiring often uses specific color wires for a particular lighting function but there is no guarantee that your trailer uses the common wire colors. This just means that you'll test the wires on the trailer to see what each one does; then…

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Answer 8

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 9

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 10

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 11

The difference between an load range C and load range D tire in the same size is the capacity and psi rating. The two tires will still have the same dimensions and fit on the same wheel. The D rated tire has a higher capacity. For a ST175/80D13 like…

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Answer 12

Load range B trailer tires are going to have a lower capacity than C load range tires. Basically that, psi rating, and the ply rating are the only differences. A higher load range tire would last a little longer than lower load ranges of the same…

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How to Determine Trailer Wiring Color Functions

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