When backing Ford f-150 up on any kind of an incline rear end is locked up for about ten seconds causing a safety risk. When shifting from reverse to drive. Ds not do this on a flat surface. Have almost been hit three times now by cars coming around the corner of my street. Ds not throw a code. Been at dealership a couple weeks. Dealership sent tech to house to observe. Did it every time! Truck only has 800 miles on it.