NHTSA Complaint #11714905 — 2026 GMC TERRAIN

The contact owns a 2026 GMC Terrain. While driving at 28 MPH, the RPM became elevated to over 3,000 RPM. There was no warning light illuminated. The contact immediately pulled over and then resumed normal operation after the failure. The vehicle was taken to the dealer to be diagnosed; however, no cause for the failure was found. The contact was advised to bring the vehicle back to the dealer if the failure reoccurred. Approximately one week after the initial failure, while driving approximately 30 MPH, the transmission unexpectedly downshifted to L2. There was no warning light illuminated. The contact pulled over and restarted the vehicle, and the vehicle was taken back to the dealer. A diagnostic test was performed, and the contact was informed that the transmission needed to be rebuilt. The manufacturer was notified of the failure and was provided a case number. The vehicle remained with the dealer unrepaired. The failure mileage was approximately 1,300.