DT*: THE CONTACT STATED WHILE DRIVING 48 MPH, THE VEHICLE WAS HIT BY ANOTHER VEHICLE ON THE REAR PASSENGER SIDE. THE SEATBELT DID NOT AUTOMATICALLY LOCK, THE LENGTH OF THE BELT WAS NOT CONTROLLED BY THE SHOULDER BELT RETRACTOR. THE AUTOMATIC LOCKING RETRACTOR DID NOT FUNCTION AS IT SHOULD BE AND THE PASSENGER IN THE REAR RIGHT SEAT OF THE VEHICLE SUSTAINED SERIOUS INJURIES. THERE WERE NO WARNING SIGNALS PRIOR TO THE INCIDENT. THE VEHICLE WAS TAKEN TO AN AUTO REPAIR SHOP.