Speedometer not working

Make sure the differential and auto box are not short of fluids. Many ABS systems take a sensor reading on the differential. If there is evidence that the pinion oil seal has been leaking (diff wet with oil and permanent oil drip at bottom) then it is very likely that the diff is in need of replenishment. The heavy shifts are probably unrelated and are due to low transmission fluid: should be able to refill via the gear fluid dip stick tube

Same exactand issue withif my 2002 F-250. Dont mess with any sensors until ALL fuses are physically inspected. I dont care what any master technician tells you. I am a controls specialist for Siemens and the Ford dealership told me it was my ABS module after telling me they found a short and had fixed it and replaced my VS sensor on the rear diff. They didn't troubleshoot it andand I doubt they have the mentalcommon capability. I'm surprised they can complete an oil change on their own. I found 3 weak fuses and replaced them. Problem solved. This could have been lead from a short in the wiring for the overdrive disable button on the shifter. If you have an automatic trans. Be sure to inspect this prior to replacing fuses so you dont burn any new ones. I believe the ones I found bad were 24,25 and 26. I went ahead and replaced every fuse since the cost was only a $16 kit. Ford charged me 500.00 to do nothing but lie to me.