Chosen Solution
What causes the odometer and speedometer to stop working?
Pam Francis old question and most likely no longer relevant. Probably got fixed already. Number one suspect with this is always the speed senor on your transmission. No speed sensor signal means your speedometer and odometer will not be working. Of course it can be the BCM, bad wiring, bad instrument cluster and many more parts in between but you want to start buy checking the sensor first.
