How To Wire a Trailer Tail Light with Yellow, Black, Red, and White Wires

Question

Question:

I have taillights that have 4 wires blk red yellow and white. What is each color

asked by: William

0

Expert Reply:

The best way to find out what each wire is for on your tail light is to take a 12 volt power supply and apply that to each of the wires to see which bulb it illuminates. I cannot really give you an exact function for each color as it could vary from manufacturer to manufacturer.

With that being said, we have the Fusion LED Combination Tail Light Bar part # STL264RB which contains white, black, red, and yellow wires. The functions of these colors on this lights are as follows. This may be similar to what you have but it will be best to test with 12 volt power before making your connections.

Black: Tail
White: Ground
Red: Step/Turn
Yellow: Backup

expert reply by: Conner L

0

Robert

2/7/2026

I have a 4 wire trailer light Black White Red Yellow My trailer wires are Brown Green Yellow White Witch wire goes where

Robin H.

2/9/2026

@Robert without more information on the light itself I can't say for sure. The trailer wires are likely the standard, brown is running lights, green is right turn/stop, yellow is left turn/stop, and white is ground. White is probably power on that light, yellow I would try matching with yellow and then you can connect and test the others to see what the functions are. It won't hurt the light if you wire it incorrectly so if you don't have a wiring diagram or other information on the light trial and error is your best bet.

Answer 1

This is a common question we get on lights like the LED Trailer Tail Light with License Bracket part #328-003-81LBM1. The original colors you have are the traditional trailer wiring code so brown=taillights, red=turn/brake and white is ground. On…

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Answer 2

It is likely that the red wire on your old lights is the turn signal/brake light wire, and the black wire is the running light wire. That would make the white wire the ground. You can verify this by testing the wires using a circuit tester such as…

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Answer 3

If the wires from your trailer are good and the power is good, then we just need to figure out what each wire on the light itself does. The best way to do that is to take a 12 volt power supply and apply that to each of the wires on your lights to…

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Answer 4

You have it right so far, the 4-way connector is just as you have stated. Remember that Yellow has a L in it so that is the left side brake/turn signal and green has a R in it so that is the right side brake/turn signal. The colors for wiring a 7-way…

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Answer 5

You should have 3 wires at the rear of your LED light, or from a pigtail like part #A47PB, that plugs into a light like part #STL22RB. The red wire will be connected to your stop/turn circuit on your vehicle. The black wire is spliced into your…

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Answer 6

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Answer 7

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 8

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Answer 9

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Answer 10

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

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Answer 11

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Answer 12

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How To Wire a Trailer Tail Light with Yellow, Black, Red, and White Wires

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