Wiring Configuration for Trailer Side Marker Lights

Updated 11/30/2016 | Published 11/29/2016

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16 Gauge, 4 Conductor Bonded Parallel Wire - Per Foot

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Screw - Self-Tapping Phillips Head - 8-18" x 3/4"

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Dielectric Grease for Electrical Connectors, 2 oz.

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Question:

there is a brown and a white wire coming out of the sidelight. I used a wire connector to attach both brown wires but not sure where the white goes .Is it a grounding wire? Do I drill a hole and attach a screw to wrap around it if so?

asked by: Tim

Expert Reply:

The usual configuration for 4-pole trailer wiring has the WHITE wire as GROUND, the BROWN wire as RUNNING LIGHTS, the YELLOW wire as LEFT TURN/STOP and the GREEN wire as RIGHT TURN/STOP. If your light has white and brown wires coming out of it then typically the brown wire would connect to the + side of the running light circuit and the white wire would ground to the trailer frame, or could be run up to the trailer plug's ground. One way or the other the light must have a ground and a + connection.

If you want to ground the light to the trailer frame you can use a self-tapping screw like # 1131832. Make sure the ground point is clean bare metal and if you want to you can apply dielectric grease # 11755 to help protect that ground connection from dirt and moisture that could cause corrosion.

expert reply by: Adam R