The ground terminal directly above the sensor was rusted pretty badly. I would have liked to take that off and clean it, but there is no way of getting that bolt off without dropping the diff, so I just cleaned it with a small wire brush and sandpaper then cleaned the wire as best I could. So far so good, but I am not impressed with that ground location so I am sure I will be either relocating or coming up with a better connection in the future. Probably next spring after another round of salt and snow....