Why does your speedometer not work and the transmission shift erratic and odometer not work this is on on 1995 Buick riviera supercharger and the problems happened all at once?

The issues with your 1995 Buick Riviera's speedometer, erratic transmission shifting, and non-functional odometer likely stem from a failure in the vehicle's Vehicle Speed Sensor (VSS). The VSS provides essential data to the engine control unit for both the speedometer and transmission operation. If the sensor is malfunctioning or there’s a wiring issue, it can cause all these symptoms to appear simultaneously. Additionally, check the vehicle's fuses and connections for any signs of damage or corrosion.