Both Trailer Turn Singles Blink at the Same Time on a Trailer Towed by a 2008 Chevy Silverado

Published 10/24/2012

Question:

I have a 2008 silverado and when I turn on left turn signal both blink on trailer using seven prong to four flat adapter

asked by: Alan

Expert Reply:

Typically when both blinkers flash at the same time it is either a ground problem or a corroded or miswired connector or adapter. First examine the trailer side connector and the vehicle side connector and clean out any dirt or corrosion. Also check the adapter.

If that does not fix the issue make sure that the vehicle and main trailer connector grounds are attached to clean and corrosion free bare metal surfaces. Do the same for the trailer lights. A bad or weak ground can cause all sorts of issues.

Next you can check to see that the connector on the truck, the adapter, and the trailer connector are all compatible. I have included a link to a wiring FAQ with diagrams of how connectors are wired. On a vehicle side 4-Way you will have one exposed pin and that is the ground. Next to that is the running light pin, followed by the left turn/brake lights, and the last pin is right turn and brake lights.

expert reply by: Michael H