The contact owns a 2019 GMC Sierra 1500. The contact stated while driving at approximately 25 MPH, an abnormal sound was coming from under the floorboards. No warning light was illuminated. The contact had taken the vehicle to a local dealer, where it was diagnosed and determined that the transmission oil pump had failed and the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 158,000.