Troubleshooting Both Turn Signals Coming On with Just Left or Right Activated

Updated 05/25/2018 | Published 05/24/2018

Question:

I hooked up everything right,but when I turn on left or right blinker ,both lights blink at same time.what to do fix problem

asked by: Dustin R

Expert Reply:

If both turn signals are turning on with just the left or right signal activated on the tow vehicle, this means that the two circuits are shorting out to each other somewhere along the wiring on your tow vehicle or trailer.

I first recommend using a circuit tester like # PTW2993 to test the connector at the rear of your tow vehicle. You can have a buddy run through the lighting function inside the cab while you test the pins on the connector. If you find that both the left turn and right turn pins are powered with just one side activated, then you know the issue is somewhere on the tow vehicle side. You will want to check the wiring harness for any damaged or exposed areas that might be touching each other, fixing as needed.

If you get the appropriate power at the connector, then the issue is somewhere on the trailer side. You will again want to check for any damaged or exposed wiring along the trailer. Also check to make sure the trailer side connector is free of any debris or corrosion that might be bridging two pins together and causing the short.

I have attached a wiring troubleshooting article that you can also check out.

expert reply by: Chris R