On January 16, 2024 We had been driving in 4 wheel drive. When we arrived home put the truck in 2 wheel drive, then in park, set the emergency brake and got out. We went in the house. A minute or two later the alarm on the truck started up. When I opened the door the truck was rolling down the driveway into the street. On January 17, 2024 We again had been driving in 4 wheel drive. Arrived home put it back in 2 wheel drive, put it in park, set the emergency brake and got out. My husband sat in the driver's side while I got my twin granddaughters out of the passenger side because the driver's side rear door doesn't work properly in icy weather. As I as unbuckling my granddaughter's seat the truck began rolling down the driveway. I had to run away from the truck. I ended up hitting ice, falling on my back and hitting my head hard. Later in the day we took it out and tried it again and had the same results. Even with the truck in park and the emergency brake engaged the truck rolled down a slight incline.