Well more info would help. what sensor did you replace? May be the one on the rear axle, top of the pumpkin? If not then that's what you have to replace. If so then you have to either jack up your rear axle so both tires are off the ground pull the diff cover. Look at the tone ring. That is what the Rwal sensor reads.(rwal means rear anti lock) The tone ring is inside the diff. right along side the ring gear. It has a bunch of teeth on it. If the teeth are broken or bent then the sensor won't read right. spin the diff all the way around look closely if one tooth is missing it's bad.Now the bad news if those teeth are damaged, some thing came apart to damage them. Usually the diff clips. Also the speed sensor on the tail of the trans. Called an output speed sensor. Can affect your speedo. But normally doesn't set an abs light. You did not tell me any codes so I don't know.
