How to Install New Trailer Lights that Only Have One Wire

Updated 10/07/2024 | Published 05/18/2015

Question:

oneon my 1997 airstream the old light have two wires the new ones have one

asked by: Mitchel G

Expert Reply:

A trailer light that only has 1 wire means that it grounds through its mounting hardware. The single wire is the power wire. The best surface to ground a light to is steel. If steel is not available in the area the light installs you can attach a ring terminal and wire to the grounding stud and attach the other end of the wire to the original ground wire from the old light.

expert reply by: Michael H

Abeja

5/22/2024

I would assume the current needs to return to the vehicle. Is there a line from the plug that also goes to the steel frame?

Jon G.

5/28/2024

@Abeja Your trailer plug should have a ground on it as well, yes. Typically this is a white wire but sometimes a shop will use a different color wire if they don't have white.

Roger

10/6/2024

@JonG So if marker light has only one wire and trailer has ground and power, what us to be done with the ground that would typically go into light?

Jon G.

10/7/2024

@Roger If the marker light only has 1 wire then that means it grounds through the hardware so that 1 wire will need to be connected to the running light function.