Troubleshooting Trailer Taillights Not Functioning  

Question:

Expert Reply:

The first thing I would check would be ground issues that might be on your trailer. Typically ground problems can cause all sorts of bizarre behavior including what you are describing. Look for for any wiring issues such as cut or exposed wire as well as corrosion and fix as necessary.

If that checks out I would test the running light circuit on your tow vehicle to see if the problem lies on the trailer side of the equation or the vehicle. I would recommend you use a circuit tester like our part # 3808 for this. I attached a video on how to do this for you to check out also.

If there is voltage on the vehicle trailer connection then you know the problem is in the trailer wiring and should be checked and fixed as necessary. If there is no voltage at the vehicle trailer connector you know that the problem is in your vehicle and you will want to trace the wiring up looking for anything that would cause the problem and fix as necessary.

expert reply by: Jameson C

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