Troubleshooting Trailer Running Lights After Installation of Light Kit

Question:

Hi I have a 2003 Toyota Sequoia SR5. I installed a tekonsha trailer light kit to tow my boat and I cant figure out why I have no tail light. Turn and brake lights work fine. The boat trailer lights work fine connected to our other vehicle. I did troubleshoot that the pin for the brown wire on the sequoia has no power to it. I also checked all the fuses related to trailer lights and the all look good. The vehicle did not have a relay in the tow tail slot so I purchased one and plugged it in hoping that would fix the problem but no luck. Any help would be greatly appreciated. Thanks

asked by: Frank P

Expert Reply:

Often when trailer lights funtion except the tail or running lights the issue is a bad ground. Unlike stop and turn lights that come on an off, running lights remain on and this means they pull more current. A weak ground may still allow those other functions to operate and reveal itself only when your load draws higher current, such as when the taillights are on.

Check the main white ground wire on both the vehicle harness and the trailer harness. (Focus on the vehicle since the trailer works with other trucks.) These connections should be made to clean bare metal surfaces. You can sand off the grounding points to provide a clean surface and apply dielectric grease like # 11755 to help protect those connections. If you prefer you can move the grounding point to new points on the vehicle and trailer.

expert reply by: Adam R