How do I Wire a Marker Light That Only Has 1 Wire To My Trailer?

Updated 06/01/2021 | Published 05/29/2021

Products Featured in This Question

LCD Digital Circuit Tester

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Deka Ring Terminal - Heat Shrink - 16-14 Gauge - 1/4" Ring ID - Nylon Insulation - Blue - Qty 1

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$2.37

Question:

There are 4 wires coming out from the trailer for marker lights 2 white 2 green. Only one wire coming from marker. Which wire do I need to install?

asked by: Dan M

Expert Reply:

The 2 white wires should be for your ground connections. These can vary depending on who wired the trailer lights. A Test Light # PTW2992 can be used to determine which wires receive power when the lights are on.

When the lights were initially installed they ran one set of wires to the marker light and then another set to the next light. This is why you have 2 of each color.

The one wire coming from the marker light will connect to the green wire or whichever wire is the positive side of the wires that you have. If your wiring system is grounded through the trailers frame and you are connecting the new light to a part of the chassis it will not require to be connected to the 2 ground wires. If the light does not connect to a ground location you will need a Ring Terminal # DW05737-1 to connect to the mounting stud that carries the ground circuit. It is very important to ensure this is insulated from any chance of combustibles or water infiltration.

expert reply by: Bud M