Troubleshooting Trailer Blinkers that Operate Both Sides of Trailer Lighting

Question:

I installed a curt t1 connector on my 2009 kia optima. Plugged it into the trailer and when I put the signal on to turn left or right both the tail lights blink. Shouldnt they work independently and if so how do I fix it? thanks for the help .

asked by: Brian H

Expert Reply:

First thing you should do at this point is test the 4-way of the wiring harness with a circuit tester part # PTW2993 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached.

If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. Most likely there is a short between the two stop turn circuits on the trailer from exposed wire that sends both of the blinker circuits to both sides of the trailer.

I attached a help article on troubleshooting 4-way installs and trailer wiring for you to check out as well.

expert reply by: Jameson C