NHTSA Complaint #11478276 — 2017 GMC SIERRA 3500

Brake are very spongy all the time we’ll While driving in parking lot at low speed we lost brakes happen to hit person in front. This has been a continuous problem to point we are scared to even use the truck to go to store. Took it to Firestone. They told me it was the master cylinder. So they replaced that, replaced the front rotors and pads, did a fluid exchange abs as well? Don’t know what that is. On the internet there is tons of this issue. I even see GMC 1500 is having this issue and there is a recall for the recalibration electric brake controller? Couldn’t it include the full Sierra line?. Why not on the 2500, 3500? Looks to be same system? Rotors and calipers are different thats it If anyone can help please let me know. It’s not covered under warranty and they want to replace some pump for $1500. I just paid $1500 for something totally different