TL* THE CONTACT OWNS A 2010 LEXUS RX450H. WHILE DRIVING APPROXIMATELY 25 MPH THE CONTACT DROVE OVER A BUMP IN THE ROAD WHILE DEPRESSING THE BRAKE PEDAL. THE VEHICLE STALLED AND SUDDENLY THE BRAKES DISENGAGED. THE CONTACT STATED THE FAILURE OCCURRED SEVERAL TIMES AND CAUSED A REAR END COLLISION WITH ANOTHER VEHICLE. THERE WERE NO INJURIES AND A POLICE REPORT WAS NOT FILED. THE VEHICLE WAS TAKEN TO THE DEALER. THE TECHNICIANS WERE UNABLE TO DIAGNOSE THE FAILURE. THE TECHNICIANS STATED THE REGENERATIVE AND THE HYDRAULIC BRAKING SYSTEM BEGAN TO SWITCH FROM ONE TO THE OTHER AND CAUSED THE HESITATION. THE VEHICLE WAS NOT REPAIRED. THE APPROXIMATE FAILURE MILEAGE WAS 2,000.