The lawsuit, brought by Napa Valley G Experience and individual plaintiffs Juan Morales and Ruben Smith, targets GM's 10-speed automatic transmissions used in 2019-present Sierra, 2019-present Suburban, and 2018-present Yukon vehicles. The complaint alleges GM's transmissions suffer from what the plaintiffs call a 'system integration defect' that prevents reliable shifting and creates safety hazards ranging from harsh gear changes to complete wheel lockup at highway speeds.
According to the 71-page complaint, GM introduced its 10-speed transmission as a 'breakthrough' in performance and efficiency, but the reality was far different. The lawsuit alleges GM 'failed to design and to manufacture its 10-speed transmission platform to withstand the demands of real-world performance,' resulting in 'hesitation between gear changes, jerking, slipping, and harsh shifts' that can escalate to 'dangerous wheel lock-ups.' The complaint details how GM co-developed the transmission with Ford, giving it 'a front-row seat' to Ford's troubled rollout in F-150 trucks that was 'met with consumer complaints, industry criticism, and even class action litigation.'
The plaintiffs reserve their harshest criticism for GM's response to mounting evidence of transmission problems. The complaint alleges GM 'set up internal restriction and exchange programs through a series of service bulletins' that 'placed the 10-speed transmission and its torque converter on part restriction,' requiring dealers to contact GM's Product Quality Center before performing repairs. As the lawsuit states: 'These measures confirm that GM knew of potential concerns with the transmission, yet it chose to manage them quietly rather than to admit the truth to consumers.'
The case chronicles a series of recalls and service bulletins dating back to 2016, when GM first acknowledged 'potential concerns' with its 10-speed transmission. The complaint details two major safety recalls—one in October 2024 covering 461,839 vehicles and another in March 2025 covering 90,081 additional vehicles—both addressing the same 'excessive wear' problem that causes wheel lockup. GM admitted to NHTSA that it identified '1,888 field reports alleging a lock up' and knew of 'eleven alleged incidents potentially related to the condition, including vehicles veering off the roadway,' plus 'three minor injuries.'
The lawsuit challenges GM's attempts to limit the scope of the defect, arguing the company's recalls are 'demonstrably underinclusive.' The complaint alleges GM confined its October 2024 recall to certain diesel models 'despite documented wheel lockups in 2023 and newer vehicles' and limited to diesel applications 'even though gasoline vehicles have experienced the same lockup condition.' The plaintiffs argue this pattern shows GM continues to misrepresent the true extent of the transmission problems.
Perhaps most tellingly, the complaint reveals GM's inability to provide an actual fix for the transmission defect. Instead of repairing the underlying hardware problem, GM's recall remedy consists of 'new transmission control module software to monitor valve performance and detect excess wear.' When the software detects problems, it limits the transmission 'to fifth gear, preventing the possibility of a wheel lockup condition,' leaving drivers with 'sluggish or reduced propulsion' in a 'limp home' mode. The complaint also details how GM dealers began purchasing aftermarket valve body kits from a company called Next Gen Drivetrain, which had warned GM the defective transmission posed an 'extreme safety problem.'
The complaint seeks class action certification for California purchasers and lessees of the affected vehicles, alleging violations of California's consumer protection laws, breach of warranty, and federal Magnuson-Moss Warranty Act claims. The named plaintiffs describe experiencing the full spectrum of transmission problems: Napa Valley G Experience reports 'shaking, shuddering, harsh mechanical noises,' Morales experienced 'harsh and erratic shifting' requiring complete transmission replacement, and Smith encountered 'harsh and erratic shifting, hesitation and delayed responses, shuddering and unexpected shaking, clunking, whining' that GM dealers were unable to fix.