The sliding driver side rear door malfunctioned - either a sensor did not go off, or the door did not register the sensor. My 4-year-old female child pressed the button to automatically open the sliding door, and attempted to climb in the vehicle as it was sliding open. She accidentally hit the button again as she entered, and the automatic sliding door began to close. Her head became trapped between the sliding door and the vehicle frame, and the door continued to attempt to shut, crushing her head. She screamed and I pressed the button again, and the door began to open, letting her loose. She was in significant pain and did not settle quickly; she has a large knot and bruising on her head where the automatic sliding door trapped her, and has a headache. The door should have registered that her body was in the way of closing, and additionally should have stopped and re-opened when it made contact with her head.