General Motors is recalling nearly half a million diesel trucks and SUVs to sort a serious crash risk.
According to a new report filed with the National Highway Traffic Safety Administration (NHTSA), GM is voluntarily recalling 461,839 trucks and SUVs due to a problem that could cause the vehicles’ transmission valve to fail, in turn locking up the rear wheels and increasing the chance of an accident.
This recall campaign covers virtually all of the automaker’s full-size pickup trucks and SUVs, ranging from the Chevy Silverado/GMC Sierra 1500 to the 2500 and 3500 HDs, as well as the Chevy Tahoe/Suburban, GMC Yukon and Yukon XL and Cadillac Escalade. There is one major caveat if you’re a concerned owner, however: This recall only impacts vehicles equipped with diesel engines. As a result, the majority of the recall population includes heavy-duty trucks (where the 6.6-liter L5P Duramax V8 is a far more common sight) with the Allison-branded 10L 1000 transmission, though this also impacts vehicles equipped with the 3.0-liter LM2 Duramax inline-six and the 10L 80 transmission.
A full list and count of affected vehicles includes:
| Year, Make & Model | Units Affected | Manufactured Between |
|---|---|---|
| 2021 Cadillac Escalade (SWB) | 885 | August 17, 2020 – September 21, 2021 |
| 2021 Cadillac Escalade ESV | 635 | August 17, 2020 – September 21, 2021 |
| 2020 – 2022 Chevrolet Silverado 1500 | 66,897 | May 13, 2019 – March 21, 2022 |
| 2020 – 2022 Chevrolet Silverado 2500/3500 | 166,541 | January 28, 2019 – January 11, 2022 |
| 2021 Chevrolet Tahoe | 3,858 | August 18, 2020 – September 16, 2021 |
| 2021 Chevrolet Suburban | 2,525 | August 17, 2020 – September 17, 2021 |
| 2020 – 2022 GMC Sierra 1500 | 80,033 | May 15, 2019 – March 18, 2022 |
| 2020 – 2022 GMC Sierra 2500/3500 | 135,323 | January 18, 2019 – January 7, 2022 |
| 2021 GMC Yukon (SWB) | 2,980 | August 17, 2020 – September 22, 2021 |
| 2021 GMC Yukon XL | 2,162 | August 17, 2020 – September 22, 2021 |
What to expect if there’s an issue
GM says that drivers may notice hard shifting prior to an actual transmission control valve failure. It also says that, “excessive wear within the transmission control valve body can cause a fluid leak leading to a pressure drop that causes certain valves to move unexpectedly.” An engineer submitted a report to the company’s internal “Speak Up for Safety” program on June 5, 2024, after a customer claimed that their 2021 GMC Sierra 2500 HD locked up while towing a trailer, resulting in property damage to both the truck and the trailer. The company formally opened an internal investigation on July 16.
The excessive wear, according to GM, could cause harsh downshifting and momentary lockup of the rear wheels for less than 150 milliseconds. At the time, the company’s testing and analysis concluded that brief rear-wheel lockup was not enough for a driver to lose control of the vehicle, but the NHTSA nevertheless identified more reports related to this condition. As of September 17, an investigation of vehicle owners questionnaires (VOQs) found 1,888 field reports of “lock-up” incidents, including 11 incidents of vehicles veering off the roadway and causing minor property damage. Three minor injuries were reported, though GM says none were the result of a truck colliding with another vehicle.
What’s the fix?
To fix the problem, GM says its dealers will update the transmission control module software to “monitor valve performance” for excess wear. The new program will supposedly detect that wear up to 10,000 miles before a lockup actually occurs. When the software detects a problem, it will limit the transmission to fifth gear — instead of allowing it to shift up to eighth gear, from which subsequent downshifts could trigger a lock-up — and flash a service engine light and “reduced propulsion message” in the instrument panel. The vehicle will stay in this limp mode until the next key cycle.
Although some affected trucks will still be under warranty, the automaker will reimburse owners who paid out-of-pocket for repairs. However, the company does not specifically mention replacing transmission valves as part of this specific recall, likely shifting the issue of physically replacing worn out valves to a case-by-case basis under the vehicles’ powertrain warranty coverage. This recall campaign (NHTSA number 24V-797 or GM number N242454440) aims to install the software update to prevent the lockup condition should that software detect excessive valve wear. GM says it incorporated this update into its production trucks at the start or shortly after the start of 2022 model year production, depending on the vehicle.
This issue does not affect new trucks, but a stop-sale order is in place on used trucks in dealer inventories until the problem is remedied.
GM notified dealers of the problem on October 24, and will mail out owner notifications beginning on December 9, 2024. That process will run over the following several weeks, wrapping up by February 28, 2025.
