Now worries, there is a simple fix I'm sure. This might sound silly, but check your battery connections and you body ground (clean them up with a wire brush, sand paper or whatever). After you do that, leave a battery cable off for like an hour to reset your computer.
If that doesn't help, You could also have a bad speed sensor, ort he wireing in between ot the speedometer module it self is faulty. If you're calling Ford Motor Company, stop....because you're wasting your time. Look in the phone book and call 2 or 3 Ford dealers in your region. Ask to speak to the service dept, and describe your situation. If the service writer does't have an answer, then ask for the parts dept....chances are one of those guys have a solution for you. Always call more than one dealer, because if you get the same answer more than once, chances are that's your problem.
instrument clusters are cheap if you get them used...not that you'll need a new one, but just an FYI.
36ft Damon Intruder Class A - 37ft National Sea Breeze LX Class A
-Past RVs: 19ft Sportsman, 24ft Jayco, 30ft Coachmen Mirada. We had some good times.
"Im a car guy...you've been warned" lol