WHEN BRAKE PEDAL WAS DEPRESSED AT 20 MPH IT FAILED TO STOP THE VEHICLE. THIS RESULTED IN AN ACCIDENT BECAUSE THE VEHICLE RAN THROUGH A STOP SIGN. PRIOR TO THIS INCIDENT, WHICH STARTED AT 400 MILES, VEHICLE WOULD EITHER PULL TO THE RIGHT/LEFT WHILE DRIVING AT ANY SPEED. THE CAUSE OF BOTH FAILURES WAS UNDETERMINED.*AK