Short dive:
- General Motors Co. is recalling nearly 462,000 pickups and SUVs equipped with Duramax turbo-diesel engines for transmission control valves that are subject to excessive wear over time, resulting in abrupt shifting or, in rare cases, can cause locking of the rear wheels while driving, according to the National Highway Traffic Safety Administration.
- Recalled vehicles include 2020-2022 Chevrolet Silverado 1500, 2500, 3500 pickups, 2020-2022 GMC Sierra 1500, 2500, 3500 pickups, and 2021 Cadillac Escalade, Escalade ESV, Tahoe, Suburban, GMC Yukon and Yukon XL SUVs.
- While dealers will update new transmission control module software in vehicles free of charge and provide a warranty coverage program to cover any additional repair costs, replacement parts are not currently available. However, according to the NHTSA, GM is working to get the parts as quickly as possible.
Diving information:
GM pickups and SUVs equipped with diesel engines use a 10-speed automatic transmission. Similar models equipped with gas engines use a different transmission and are not included in the recall.
The 10-speed transmissions in the recalled vehicles are marketed as “Allison brand,” but the unit is manufactured by GM, not Allison Transmission, wrote Branden Harbin, executive director of global marketing and external communications at Allison, in an email to Automotive Tuffo.
“Allison Transmission has no oversight of the manufacturing process or supply base for the Allison-branded 10-speed transmission,” Harbin said.
Updated control module software will more closely monitor the performance of the transmission control valve. If the software detects excessive wear approximately 10,000 miles before a locked-wheel condition can occur, transmission shifting will be limited to fifth gear until the next key cycle.
Excessive wear within the transmission control valve body can cause a drop in fluid pressure and unexpected movement of some transmission valves. According to the NHTSA report, the stuck condition occurs during downshifts from eighth gear. Drivers may also see a “reduced propulsion” message displayed on the instrument panel.
Due to the potential safety risk of locking the rear wheels, GM has issued a stop-sale order to its dealers for vehicles recalled on October 24. Additionally, all GM Certified Pre-Owned vehicles currently in dealer inventory will be de-certified and held until repairs are completed.
Once enough replacement parts are available, the recall bulletin will be issued and dealers can begin repairing the vehicles, according to the NHTSA report.
GM will begin sending owner notification letters on December 9th.
All 2022 Silverado 1500 and Sierra 1500 pickups manufactured after March 21, 2022, and Silverado and Sierra 2500 and 3500 models manufactured after January 11, 2022 use updated transmission control software to better detect excessive wear. A software update for additional models was introduced at the start of production for the 2022 model year.
Recall chronology
GM was made aware of the transmission problem on June 5, 2024 after an engineer submitted a report based on a customer complaint to the company’s internal “Speak Up for Safety” program, which allows employees to fearlessly report any problems relating to quality or safety. of retaliation.
The customer claimed that the rear wheels of a 2021 Sierra 2500 HD pickup locked up while towing a trailer, causing property damage to the vehicle and trailer.
Based on the whistleblower’s report, GM opened its own investigation on July 16. However, the company was already aware that excessive wear of a control valve in these transmissions was causing abrupt downshifts and, in rare cases, momentary locking of the rear wheels. . GM’s initial testing and analysis determined that the condition was not sufficient to cause loss of control of the vehicle, so no recall was issued at the time.
But on July 29, NHTSA notified GM that its vehicle owner questionnaire monitoring process had identified additional potential transmission problems. A GM investigator completed an analysis of NHTSA questionnaires along with a comprehensive field data search September 17th. The investigator identified 1,888 field reports between January 30, 2020, and August 2, 2024, of rear wheel locks on GM vehicles potentially related to this condition.
GM also identified 11 other related crashes, including vehicles leaving the roadway resulting in property damage. Three minor injuries were also reported, but none were the result of a crash.
Based on these findings, GM’s Safety Field Action Decision Authority decided to conduct a voluntary vehicle safety recall on October 17.
Correction: An earlier version of this story incorrectly identified GM’s transmission supplier in these recalls.