NHTSA Complaint #11674120 — 2025 GMC SIERRA 1500

While driving on the highway at 70 MPH, the truck experienced a harsh transmission shift followed by a sudden loss of acceleration and entered shutdown mode to protect the engine. The steering became stiff, all dashboard warning lights illuminated, and a message appeared on the driver display indicating a transmission issue and advising to drive with caution. The RPMs surged and the truck struggled to maintain a speed of 45 MPH while the remaining at 4000 RPM. This created an extremely hazardous situation for both me and my passenger. I safely pulled into the breakdown lane, came to a complete stop, shifted into park, and turned off the engine. Upon restarting the vehicle, the Check Engine Light remained on, and the transmission continued to shift abnormally at low speeds, including noticeable shuddering.