DTC 12: Operation Signal To Speedometer
WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
Wait for 2 seconds after selecting DTC 12. If speedometer needle moves full scale and then rests at 60 MPH, speedometer is okay. If speedometer needle does not move full scale and then rest at 60 MPH, replace instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION.