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Troubleshooting Marker Lights Not Working on Trailer with Wishbone Wiring


So my marker light aren’t working and I connect it to the brown wire is that right I have brown and yellow on driver side of trailer and passenger side got green and brown so are they supposed to be connected to the brown wire


Expert Reply:

It sounds like you have a wishbone wiring harness on your trailer that uses two running light wires (one for each side of the trailer). The running light wire on a trailer should be brown. The yellow wire should be for left turn/stop and the green wire should be for right turn/stop. It sounds like you have everything wired up correctly.

If the marker lights aren't working at all I recommend inspecting both the trailer side and vehicle side connector for any debris or corrosion inside the pins, cleaning out as needed. You can then test the vehicle side connector with a circuit tester like # 40376 to make sure you are getting appropriate power with the lights activate on the vehicle. This will at least allow you to determine if the problem is on the vehicle or trailer.

Also check to make sure all your ground connections on the trailer are made to clean, bare metal surfaces. This goes for the marker light assemblies themselves as well, whether they ground through a dedicated wire or through the mounting hardware.

If you are unable to locate and resolve the issue please let me know and we can continue to troubleshoot.

expert reply by:
Chris R

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