I did a search on the forum and didn't come up with anything about this. It doesn't apply to me but it might apply to some new rigs, not sure if they come with an OEM brake controller.
Found this on a recall site.
"Ford Motor Company (Ford) is recalling certain model year 2016 E-350 and E-450 vehicles manufactured November 3, 2014, to December 10, 2015 and equipped with a 6.8L engine and an optional trailer brake controller. The trailer braking system may fail, increasing the distance needed to stop the vehicle."
Ford E 450 recall