I took my 2017 Silverado in this past Sat for the reprogram, then a few days later was in bumper to bumper traffic and the brakes wouldn’t work (no vacuum at low speeds), almost wrecked. Just took it to the dealer and they said they have been waiting 2 weeks for vacuum pumps for other vehicles. So now I will be without a truck for a while. They said they would give me a loaner “car” but I need a truck to haul something this week. GM is treading on thin ice