The contact owns a 2007 BMW X5. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed, and the brakes delayed in responding. The failure had occurred on several occasions. No warning lights were illuminated. The vehicle was taken to an independent mechanic, where it was diagnosed that the secondary hydraulic pump needed to be replaced. The contact researched and was made aware of an unknown NHTSA Campaign Number; however, the VIN was not included. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 217,000.