WHEN APPROACHING AN INTERSECTION, THE BRAKE PEDAL WAS UNABLE TO BE USED, LOCKED UP. WITH NO BRAKES, THE RESULT WAS A COLLISION. THE FRONT COLLISION DETECTION THAT CONSTANTLY WARNED FALSELY ON THE DASH. THIS FAILED TO WORK PRIOR TO THE COLLISION AT THIS TIME. AUTOMATIC BRAKES DID NOT ENGAGE EITHER RESULTING IN A SERIOUS CRASH. NISSAN DEALERSHIP IS INSPECTING THE BRAKE BOOSTER, AND BRAKE SYSTEM.