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1999 7.3 F350 longbed 4x4. My speedometer and odometer are not working. Overdrive light is blinking as well. Speeding up to 35-75 mph depending on how it’s feeling that day fixes the issue until I slow back down. Already replaced the ABS/speed sensor and didn’t fix it. Whole truck also randomly jerks back and forth randomly until I pull over and turn it off and back on again and then it’s fine, don’t know if that’s associated. Please help! Just a sailor trying to learn how to work on his truck.
Pulling codes would be the first step if the VSS didn't fix it. Everyone here seems to be using ForScan, I've got something else so can't help with that. Regular code readers won't work on our trucks.
With a scanner you could also check to see if the PCM is getting information from the VSS, which would help in figuring out if the VSS wiring is shorting since you know the VSS is good.
Motorcraft VSS? Any rear diff work or damage lately? How about wire connector condition?
Theres not much besides the rear diff tone ring and sensor that mess with the speedometer in these trucks. I don't think I've every heard of a cluster stepper motor problem before.