When towing a trailer with my 1 ton gm van down hill and braking the front end shakes almost uncontrollably. the manufacturer knows about it as they have it in the owners manual. they claim the brakes get hot and to down shift the van. they also say failure to do so could result in a complete loss of brakes and a crash. gm tech says on my repair order that when brakes get hot they will pulsate then when they cool they go back to normal. per tac no repairs at this time case [xxx]...[xxx]. all 1/2 ton, 3/4 ton, and 1 ton vans are in this category as no specific model of savana/express was mentioned in the owners manual. obviously a design flaw they knew about in the beginning and chose not to do anything about it. information redacted pursuant to the freedom of information act (foia), 5 u.s.c. 552(b)(6).*tr