Troubleshooting Turn Signals that Both Come On when One Blinker Is Activated

Question:

When I turn on the either the left or right turn signal both lights flash as if the hazard lights are on. I believe the blub and socket kit is installed correctly. do believe it is a problem from the towing vehicle..

asked by: Nick P

Expert Reply:

What that means is that the turn signal circuits have somewhere shorted out to each other on either the wiring of the towed vehicle or the tow vehicle. The easiest way to determine where the problem is is to use a circuit tester like our part # PTW2993 on the connector of the tow vehicle to test to see if both circuits activate when one blinker is applied. If so, the problem is the tow vehicle and you will want to check the installation of the wiring harness looking for corrosion, cut or exposed wire or anything else that would cause the short and fix as necessary.

If the voltage looks good at the connector you tested the problem is on the towed vehicle bulb and socket wiring. Most likely the problem would be in the connector that was installed. Exposed wire would be the most likely candidate.

I attached an FAQ on 4-way installs for you to check out as well.

expert reply by: Jameson C