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New Trailer Lights have 3 Wires but Old Trailer Lights have 4 Wires


The new light assemblies have three wires, white, brown, green where as the existing lights have two green one white one brown. Are the new lights compatible?Which wires do I connect together. Thanks


Expert Reply:

You will need to determine what the functions of the wires are on the existing lights using a circuit tester like # PTW2993. Have the trailer connected to a vehicle and have someone run through the light functions to determine what the wire functions are.

Trailer light # 30-92-001 has a white ground wire, green for running lights, and black for brake lights and turn signals. On your trailer wiring, the white is probably the ground if it was attached to the frame. The brown wire is most likely the running lights and one of the ground wires is brake and turn signal.

The other green wire I cannot be sure unless your trailer has separate turn signals and brake lights. Testing the wires will confirm what their functions are.

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