A DRIVER PARKED HER VEHICLE SUCH THAT THE REAR OF HER VEHICLE WAS FACING DOWNHILL. SHE THOUGHT SHE PLACED THE VEHICLE IN PARK AND TURNED THE IGNITION OFF. SHE LEFT THE KEY IN THE IGNITION AND BEGAN TO CLEAN THE INTERIOR OF THE VEHICLE FROM THE FRONT PASSENGER SIDE. HER TWO YEAR OLD SON WAS STANDING ON THE DRIVERS SEAT. WHILE SHE WAS CLEANING THE INTERIOR, SHE HEARD A CLICK AND THE VEHICLE BEGAN TO ROLL BACKWARDS. SHE WAS UNABLE TO STOP THE VEHICLE FROM ROLLING BACKWARDS. SHE WAS INJURED BY STATIONARY OBJECTS LOCATED OUTSIDE AND ALONG THE PATH OF THE MOVING VEHICLE. A REVIEW OF THE OPERATION OF THE GEAR SHIFT LEVER FOUND THE FOLLOWING: IN THIS VEHICLE, IT WAS POSSIBLE TO POSITION THE GEAR SHIFT LEVER BETWEEN THE PARK AND REVERSE POSITIONS. IN THIS INTERMEDIATE POSITION, THE GEAR SHIFT LEVER ENGAGED THE PARKING PAWL IN THE TRANSMISSION SYSTEM WHICH PREVENTED THE VEHICLE FROM MOVING. HOWEVER, THE GEAR SHIFT LEVER WAS NOT LOCKED IN POSITION, AND THE LEVER WAS MOVABLE. A FORCE WAS NECESSARY TO OVERCOME THE RESISTANCE HOLDING THE LEVER IN THE INTERMEDIATE POSITION. THE FORCE COULD HAVE BEEN CAUSED BY LEVER CONTACT OR VEHICLE JOSTLING. THE LEVER MOVED, AND THE PARKING PAWL RELEASED THE WHEELS ALLOWING THE VEHICLE TO MOVE. IN NORMAL PARK MODE, THE OPERATOR MAY PLACE THE GEAR SHIFT LEVER IN PARK AND THE LEVER WILL LOCK. IN ORDER TO TAKE THE VEHICLE OUT OF PARK, THE IGNITION KEY NEEDS TO BE IN EITHER THE ACCESSORY OR RUN POSITION AND THE BRAKE PEDAL MUST BE