2020 AT4 6.2L 10 speed problem

[Scott66s]

OK. I have a 20 AT4 6.2L 10 speed Crew cab. A couple weeks ago I received the brake reprogram recall notice from GM so I made an appointment to have this done yesterday. Let me say first that bought this 30 Jan 20 and I have had zero problems with my brakes or the driveability of this truck. The engine and transmission have been flawless till now. Extremely powerful and smooth shifting.

I was a bit apprehensive about getting the brake module reprogrammed but I decided to get it done because of the safety aspect. I don't want my brakes to fail like I have read the horror stories from some people on these group chats.

Well they did the reprogram yesterday. It took them about an hour and then they sent me on my way. I drove about 2 or 3 miles from the dealership and was traveling about 50mph when there was a big jerk and bang/slam in the driveline. At that moment the engine light came on and the transmission was acting like it was in neutral. I pressed the accelerator and the engine just twisted up to about 4000 rpms like it wasn't in gear so I took my foot off the pedal and with my foot off the pedal the engine revved up over 6000 rpms for about 5 seconds then went back down to idle. I then pulled over and turned off the truck. I called the dealer and told them that I was having problems and I was on my way back if possible. I restarted the truck, put it in reverse and turned around. The truck would move but the engine had to do about 4000 rpms to get moving in reverse or forward. I limped it back to the dealer. After I explained to the service writer what happened, she said "well what we did to the truck has nothing to do with my problem." I told her that I have had zero problems until they performed the recall so it obviously IS related! They took it in the shop and have no idea what is wrong so now they have put their "transmission specialist" on it. Needless to say, he can't figure it out either so they put me in a rental for now.

I am waiting to hear from them today.

Has anyone on here got any insight on this or heard of this problem after a brake module reprogram? I would think the brake system has nothing to do with driveability but it seemingly does.

[Jsdirt]

I have no idea how a 2020 is set up, but even in vehicles 13 years old, every module communicates with the other, throughout the entire vehicle. I can only imagine what they've engineered for 2020.

 

Either way, sounds  to me like a major screwup on either GM's end with buggy or mis-engineered software, or, something happened during the upload on the dealership's end (more likely). Battery could've died and corrupted or even bricked a module or 2, or their internet, or computer is slow and corrupted the upload. Lots of things can go wrong during the process. Sounds like a few things did.

 

Bottom line - they need to fix it. Regardless of what the cause is, you are under the bumper-to-bumper warranty, unless you've already put over 36k miles on the vehicle.

[Scott66s]

3339 miles on it.

Edited April 2, 2020 by Scott66s

[Jsdirt]

Yep - you're covered.

 

If this dealership can't handle the repair, or gives you a hard time, you'll have to find another. This is GM's problem, NOT yours.