FADEC

I have a 2016 8 speed that is also a major vibrator. Usually on interstate cruising between 70-80. Console and seats vibrate pretty good. Seems to come and go. Will vibrate for several miles, then be smooth for a few miles. BTW my steering wheel does NOT shake. Just the seats and console.

I think my torque converter one of my issues as well. Doesn't matter what you think. If they "can't find anything wrong" with it then NOTHING is going to get repaired

I also have the 8 speed that shifts terrible . Very harsh, rough shifts. Yes I have had in in for service twice at two different dealers. There is nothing they can do to fix it. It doesn't matter what you tell them or what bulletins etc you show them. They cannot and will not fix it. You have to pick your battles and this is one battle I will not win. It's in the shop now for a rough idle and driveline vibration that I get on the interstate between 70-80 mph. Been in the shop for over a week. Got a call on day two saying they couldn't find anything wrong with it. Haven't head anything from the dealership in almost a week. Have no idea what's going on they won't answer the phone or return calls. BTW they gave me a cheesy little Chevy Cruze as a loaner. That thing is 1000% smoother than my truck!! Smooth idle, smooth shifts, rock solid driving down the interstate. I saw the window sticker it was 21k. My truck was over 51k. Thinking about looking at some Fords or maybe a Tundra, but I know I'll take a huge hit on depreciation and I don't know if I can swing that.

Mine seems to run around 40-43F. Thats what it ran this last weekend driving down the interstate with air temps 88-91F. It sucks to have a vehicle that the AC never really works great. Had one,couldn't deal with it, traded it.

Jacob, Just got done driving about 20 miles in various conditions. No change from driving in M7 except worse MPG from the higher RPM's on the highway.

Jacob, Did you try driving around in M7 to see if it went away or improved?? I will try mine out tomorrow. If its as simple as disabling the AFM then there plenty of tuners to override that. Not saying that you should have to override it on 50k truck to get a decent ride though!!

I'm right at 4100 and still pretty harsh. Will keep driving and see if it goes away.

Wanted to add that I almost think it is a torque converter issue. I was somewhat of a gear head back in the day, and it almost feels like the torque convertor is reengaging when coming to a stop. Almost like driving a manual and leaving it in first when coming to a stop and not pushing in the clutch. Has that jerky solid engagement feeling. if that makes any sense!!

Brossee01, Not to be the bearer of bad news but my 8 speed has the same jolt as yours. Has had it since new, now with 4100 miles on it. Dealer did a relearn, no change. These transmissions are NOT the smooth transmissions of GM past. BTW my truck is the same as yours.

I traded in a 2009 Avalanche as well. The 6l80 was a nice tranny. Always very smooth!!

Since there is only 2 votes for hating the trans and 17 for loving it. Clearly most love it and have no issues. I wonder what it actually is?? Something not assembled correctly inside?? Something going bad?? Some debris or something left inside during assembly?? Now I'm thinking it cannot be programmed wrong, as there are trucks made after mine and before mine that have no issues!!

Took it in for a relearn last month. 1000 miles on it since then. No change.

Seems like most 8 speed owners have the 6.2l. Would be interesting to hear from some 5.3l owners to see if they are affected like me.

Have never experienced a "butter smooth" shifting with this trans. Some starts, stops, better than others but never smooth. BTW truck built 12/15 4,100 miles.