Does anyone know how to adjust the delay time from when you depress the brake until the trailers brakes activate? My reason for asking. I have a 20' tandem axle with electric brakes. Recently I had it up on Jack's and tested the brakes with the tires in the air... while spinning the tires 1 at a time my truck proved to not actually activate the trailer brakes until 9 seconds after I depressed the brake pedal. If I squeezed the gain controller they would stop instantly. Anyone know the reason why?

 

The TBC provides a variable amount of current based on the speed of the vehicle. The vehicle is not moving...

In addition, there are three settings on a 2018 for brake "sensitivity" for the TBC.

 

My 2015 manual says that brake effort to the trailer is reduced below a truck speed of 11 MPH to reduce jerkiness when coming to a stop at low speed. If your truck is stationary during this test, that would be my guess as to why you observed this.