The back tailgate door, when opened, will go up to desired height set in car settings, then slam back down 1/4 to 1/2 of the total height. Turning off auto open and close it continues to do so. When manually pushing the door to the open position, it will continue the problem. We have had numerous incidents of heads being hit by the door, arms and hands have also been hit. We took the car to the dealership and they said the door actuator would be over $2000 to fix. It seems like this is a similar issue to the side door actuators that had to be replaced via recall.