Left Hand Turn Signal Causes Multiple Lights to Illuminate on Trailer

Question:

7 pin connector all the trailer lights work fine until i hit the left blinker then the back two trailer lights start to blink as if i turned the hazards on

asked by: Rick N

Expert Reply:

The issue you are having with your trailer lights could be caused by either a ground or wire short. I first recommend you test the pins inside the 7-way on your tow vehicle to make sure that the issue is on the trailer and not the tow vehicle. The pins should only be active when you have the respective signal applied. For example, if you were testing the left hand stop/turn pin then the circuit should only be active with these signals applied. In addition to this, the turn signal should send a pulse whereas the brake signal should be constant. If not then you have an issue with the vehicle wiring and you will need to trace the wires while checking for shorts.

If the vehicle side checks out then the first thing I would do is reground all of the trailer lights and the trailer connector to a single ground point up by the tongue of the trailer on the frame. If the issue is still not resolved after this then I recommend you trace each of the wires to left side tail lights to make sure there are no shorts.

Finally, you will want to inspect each of the trailer connectors to make sure there are no damaged pins or corrosion issues.

expert reply by: Conner L