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2020 At4 Transmission problems

Joe cox
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Supercup Enthusiast

Supercup

Posted
Posted
17 hours ago, bamorris2 said:

The new 10 speeds are junk. Stick with tried and true 8 speed.

 

I would say that it was tried and discontinued.  Most 8 speeds worked just fine, just like the 10 speeds.  The 10 speed is a better platform with newest engineering - mine is fantastic - but one man's junk is another man's treasure! 

Supercup Enthusiast

Supercup

Posted
Posted
17 hours ago, bamorris2 said:

The new 10 speeds are junk. Stick with tried and true 8 speed.

Tried and True 8 speed was "discontinued " after a few short years  - 10 speeds are latest and greatest - time will tell - but mine has been great.

 

One man's junk is another man's treasure! 

Ltz73 Enthusiast

Ltz73

Posted
Posted

My 8 speed in my 2018 Sierra was total garbage. After numerous attempts by dealer to resolve all the issues even they gave up and started with the “can’t replicate it” and “that is normal” BS. I finally threw in the towel and got a 2020 with the 10 speed.  Best move I ever made, it is a dream! Smooth quick shifts no clunking, jerking, slipping torque converter. Getting rid of the 8 speed transmission is long over due by GM if you ask me. 

  • 10 months later...
Lee dillard New Member

Lee dillard

Posted
Posted

So my 2020 150p ltz with 3.0 and tenspeed broke down 30 days ago with 13000 miles on it code said trans module put a new one in threw the same code replace wiring harness between ecm and module threw same code then said to replace ecm threw same code now rhe engineer want to string wires like rewiring a 1992 hewes bonefisher flats boat filed a lemon law today 

  • 1 year later...
Marco TX New Member

Marco TX

Posted
Posted

Have a 2020 AT4 Diesel, and the transmission is already out.  Waiting on dealership to repair.  Told me that they had 2 transmissions in front of it.

 

 

  • 3 months later...
Crozet New Member

Crozet

Posted
Posted

2020 GMC Sierra 1500 AT4 3.0L Duramax
 

So, I have 39k miles on this bad boy. I love the truck but have had major problems. 
 

Check engine light come on the first time. Codes for transmission. Took back to the dealer, said they it was fine. Engine light went off there- 15k miles. 

 

22k miles light came back on, took it in, same thing. 
 

28 k miles light came of, went off later that day. Fast forward, came off the highway at 39k, you could hear something break. Limped home, clunking the whole way. Towed to the GMC dealer- transmission shot.
 

GMC replaced the transmission as of yesterday- 8/26/22.

 

driving home, check engine light back on. I haven’t checked the code yet but let’s just say I’m pissed.  

  • 2 weeks later...
MyDefectiveGMC New Member

MyDefectiveGMC

Posted
Posted

So love my AT4 3L diesel but since April had nothing but trouble with the transmission. They flew in a GM engineer. He said it was a module. It finally came in. Changed it out. Didn't go 10 miles down the road before it started doing the same thing. Now they've changed out the transmission. Didn't even take it for a test drive after replacing it very next morning had the same problems.. now they're telling me they're supposedly an update coming out in October that will fix it. Meanwhile I have 50K plus vehicle that is practically undrivable. 

Greyhound6.2 Enthusiast

Greyhound6.2

Posted
Posted

I have a 6.2 with the 10 speed and developed a gear whine, it has run fine no CEL and shifts fine no problems just high pitched whine, dealer wants to put a new transmission in it waiting to hear back tomorrow on timeframe. how long have you guys had to wait to get a new transmission? 

 

ajs800 Enthusiast

ajs800

Posted
Posted (edited)

My 2020(5.3) at4 10spd started acting up around 14k miles and was replaced 2wks ago at 38k miles.   I have zero confidence in the new one. 

Edited by ajs800
  • 1 year later...
Tammy N New Member

Tammy N

Posted
Posted

We have a 2020 GMC 1500 sierra 5.3l 10sp

elevation pkg. 2nd owner. We bought extended warranty… highest one we could get with dealer 50k. We have had for 1 1/2 years. Reached 135k friday. Previous week shutter started. Dealer said needs new one @$6k because we aee out of warranty.

i have been researching today and finding all kinds of problems notes on 10sp, tgat gm knows about.

we don’t have back up vehicle and we don’t have $6 k to fix. I am in process of getting with the service manager… then i will keep moving up the “chain” until i get results of them backing theor product and replacing no cost. If that doesnt work… looking at lawsuit! Is tgere a class action on the 10sp?

  • 11 months later...
theAT4 New Member

theAT4

Posted
Posted

2020 at4,122k , 5.3 10 speed

hey i Have this truck since cero miles most miles on hwy I've been with this shudder about 5 months , now.. this kind of issue is common on GMC  trannies , at the moment I really dont know how to proceed is my only vehicle.

but sometimes it feels like is grinding something with tires , sometimes is pulling back and so on , some people says AMZOIL does a fix but who knows . the only thig that I can think of class action law suit because historie of this companie says they been seeling this vehicles knowing this issues

2016 Sierra Owner Senior Enthusiast

2016 Sierra Owner

Posted
Posted
8 hours ago, theAT4 said:

2020 at4,122k , 5.3 10 speed

hey i Have this truck since cero miles most miles on hwy I've been with this shudder about 5 months , now.. this kind of issue is common on GMC  trannies , at the moment I really dont know how to proceed is my only vehicle.

but sometimes it feels like is grinding something with tires , sometimes is pulling back and so on , some people says AMZOIL does a fix but who knows . the only thig that I can think of class action law suit because historie of this companie says they been seeling this vehicles knowing this issues

There are a few class action law suites already against GM for the 8 speed transmission issues. I don't think any have gotten resolved so I wouldn't hold your breath or wait for that outcome. 

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