During our last trip, we got an ABS/Brake light warning light in our 1999 E450 chassis RV. The lights came on about 1,000 miles into our 3,000 mile journey. We finished the trip with the lights on without incident. When we got home, I replaced the rear differential speed sensor and the lights cleared. It took about 20 minutes to replace the sensor and the only tools needed were a 1/2 inch socket wrench, snips to cut a zip tie, and a small pry tool. I simply removed one bolt from the top of the sensor, cut the zip tie for the wiring harness to provide slack in the harness, and pried out the sensor. To install, I reversed the process. So easy and probably saved over $150 in labor. Maybe this will help a fellow camper.