Oldsmobile/Buick Repair: Odometer error, vehicle speed sensor, digital dash

Question
I have a 1991 Olds 98 with a digital dash. For the past month the digital dash odometer will go from displaying mileage to displaying "error". Then it would go back to displaying correct mileage, so something was recording mileage driven. Yesterday I brought to shop and had a motor mount replaced and the odometer has displayed "error" ever since. Could something have been pulled loose when work preformed or does the digital dash have a problem?  
Thanks,
Jim

Answer
Usually if the VSS (Vehicle Speed Sensor) wiring has been disturbed on the transmission the speedometer would also be non-functional.

Since you ONLY have an ODOMETER problem this can be caused by a fault in the cluster assembly or a wiring problem in the cluster.

Usually the cluster assembly (dash assembly will have to go out for reapir.