I have the same issue speedometer mine is electronic and zero is now 45 MPH, so I have to keep subracting 45 from 120, etc.
I think this happened when I hit the speed control by accident at the same time I turned on the windshield wipers.
Standard GM setup.
Any thoughts on a reset or it is toast?
Thanks all,
Beachguy1
92 Southwind Chevy 454