Troubleshooting Trailer Turn Signal/Stop Lights Not Working After 7-Way Install

Updated 08/11/2015 | Published 08/10/2015

Question:

Trying to convert a flat/wishbone trailer wire to a 7 blade. All lights come on but no brake or blinkers. Brake/blinker left and right are the same bulb as the running lights that are working.

asked by: Jonathan

Helpful Expert Reply:

The problem is the stop/turn signal circuit of the 7-way. The running lights for the taillights are their own separate circuit and there should be a second wire run to the taillights that carries the stop/turn circuit. I attached a diagram that shows how a 7-way is typically wired.

If your current 7-way is wired up correctly the next thing to check is the grounds of the taillights as it sounds like they may not be sufficient to power the increased amperage draw of the stop/turn circuit. Ideally you would run the grounds of the assemblies back to the main ground harness of the trailer.

expert reply by: Jameson C