TL*THE CONTACT OWNS A 2004 TOYOTA SIENNA. THE CONTACT STATED THAT THE REAR LIFT GATE CLOSES UNEXPECTEDLY AND ON ITS OWN. SHE STATED THAT IT CLOSES WITH SUCH FORCE, THAT IT MAKES IT VERY DIFFICULT TO RE-OPEN. THE DEALER AND THE MANUFACTURER HAVE NOT BEEN NOTIFIED. THE FAILURE HAS CAUSED THE CONTACT'S HUSBAND TO SUSTAIN A STRAINED BACK. THE VIN AND ENGINE SIZE WERE UNKNOWN. THE CURRENT MILEAGE WAS 20,000 AND FAILURE MILEAGE WAS 15,000.