The contact owns a 2013 Ford F-150. The contact stated that while his daughter was driving in a parking lot, she depressed the brake pedal and it became stiff. The vehicle failed to slow down as intended. The vehicle collided with a parked car. A police report was not filed and there were no injuries reported. The contact then began driving at approximately 30 MPH, the brake pedal was depressed, and he observed a grinding noise emanating from the front driver side of the vehicle. The brake pedal then became stiff and did not slow down as intended. The vehicle was placed in the park position on multiple occasions to stop the vehicle. The vehicle was taken to an independent mechanic where it was diagnosed that the check valve was clogged and the brake vacuum booster pump needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 170,000.