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My big, beautiful GMC Sierra looks great, but the drivetrain is junk.

Shannon Elizabeth (@singegneri) says her 2019 GMC Sierra Texas Edition is not what it appears to be on the outside or inside. It's a great-looking truck and was the most expensive trim level for the Sierra lineup. 

Imagine investing in a Sierra Texas Edition with luxurious upgrades like chrome wheels, Bose audio, power sliding rear window, LED cargo bed lighting, and dual-zone climate control. You'd expect to own the most stylish truck on the block. However, the reality is far from the dream, as the drivetrain in the GMC Sierra truck is the weak point.

The 8-speed automatic transmission used in the GMC Sierra, Chevrolet Silverado, Cadillac Escalade, and other models is the problem, and it's a serious issue with the trucks.

The problem is so bad that General Motors faces a class action lawsuit alleging the company knowingly sold several hundred thousand vehicles with defective transmissions. I'll explain more about the lawsuit in this report.

First, here is what Shannon says about her 2019 GMC Sierra Texas Edition truck. 

She says, "My truck might look really nice and expensive, but I'm here to tell you, it's the biggest piece of (expletive) I've ever owned in my life."

"And it's also the most expensive, funny enough. Just a warning to all those women and men who want to buy like the Denali's, the Escalades, and everything else." 

Shannon replaced her Sierra transmission at 80,000 miles.

"They all have the same transmission as my truck. I have a 2019 GMC Sierra Texas Edition; my transmission went out at 80,000 miles. It was past my warranty, but that's cool." 

However, with only 10,000 miles on the new transmission, it has to be replaced again. 

"Fast forward. Now we're at 91,000 miles, and it's going out again. That means I have had to take it to the shop again in the last six months to get it diagnosed. And I have to go through the whole process of getting a new transmission again. I will have to replace the transmission twice." 

"Explain this to me, GMC. How will you charge people this much money and you have not done anything to your powertrain in years? And, statistically, people are going through transmissions left and right."

"If you want to talk about a money racket. These big beautiful vehicles that are super nice on the inside, and their drivetrain is junk." 

Shannon's predicament is a cautionary tale for potential buyers. She's unable to trade in her truck due to its significantly reduced value, which is now less than what she owes. This financial burden forces her to keep a vehicle that runs poorly despite its aesthetic appeal. 

She laments, "And to add insult to injury, its market value has plummeted to a point where it's worth less than what I owe. I'm trapped in this predicament, forced to keep a vehicle that's more a liability than an asset. It may look pretty, but it runs like a disaster." 

GM faces a class action lawsuit.

A report from Top Class Actions reveals that Shannon's experience is not unique. Many other GMC Sierra truck owners are facing similar transmission issues. The problem is not limited to the Sierra, as the eight-speed automatic transmissions manufactured by GM are used in several other models, including the Chevrolet Silverado, the Yukon, and the Cadillac Escalade.

CBT News says, "The lawsuit claims these vehicles suffer from significant transmission issues, including shuddering and shaking in higher gears and hesitation and lurching in lower gears, even after attempted repairs. Additionally, GM is accused of instructing dealers to reassure customers that these harsh shifts were "normal."

The report says the case involves approximately 800,000 vehicles manufactured from 2015 through 2019, 514,000 of which are in the certified classes. 

The GM truck transmission is failing prematurely. 

Additionally, the GM defect transmission class action lawsuit alleges that the defect can cause the transmissions to fail prematurely. The shaking and jerking are caused by internal transmission and/or torque converter issues.

What is the problem?

This internal problem reportedly causes friction on surfaces, hydraulic systems, and gears, preventing the system from functioning properly and causing metal shavings to circulate throughout the transmission.

The GM transmission class action lawsuit says this defect, and the metal shavings circulating, causes damages to the transmission over time and requires components to be replaced.

Did GM fix the transmission problems in 2020 and newer Sierra and Silverado trucks? 

Reports say that newer models like the 2020 and 2021 Sierra and Silverado with the 10L80 transmission have also been subject to similar issues, indicating that the problems persist despite GM's attempts to address them.

Shannon has a warning for GMC truck buyers.

"So, save your money. Don't buy a GM vehicle," Shannon says as she warns other truck buyers.  

The GM defective transmission lawsuit is reportedly scheduled to be reheard in March 2025. Stay tuned. 

Have you experienced transmission problems with your GMC Sierra, Chevrolet Silverado, Yukon, Cadillac Escalade, or another GM model? If so, click the red Add New Comment link below and let us know.

Here is another GMC Sierra owners truck issues.

My GMC Sierra Pickup Has 20,000 Miles, and It Won’t Start, My New Battery Is Dead and the Dealer Says They Can’t Fix It. Check out my report here. 

I am Denis Flierl, a Senior Torque News Reporter since 2012. My 30+ year tenure in the automotive industry, initially in a consulting role with every major car brand and later as a freelance journalist test-driving new vehicles, has equipped me with a wealth of knowledge. I specialize in reporting the latest automotive news and providing expert analysis on Subaru, which you'll find here, ensuring that you, as a reader, are always well-informed and up-to-date. Follow me on my X SubaruReport, All Subaru, WRXSTI, @DenisFlierl, Facebook, and Instagram.

Photo credit: Denis Flierl via Shannon and GMC