Originally Posted by marshallr

Not sure about newer trucks, but my 14 has TWO blinker lights on each side. If one stops working and the other continues to work you will get the fast blinker. Unless you know you are supposed to have 2 turn signal lights on each side it is easy to miss. Once I figured that out just replaced both bulbs at the same time. They only came in a 2 pack at the parts store.

Originally Posted by Sturmgeist

You can turn this off in forscan. I did it yesterday when I switched all my tail bulbs to LEDs