K 2500 Truck 4WD V8-454 7.4L VIN J SFI (1997)
Speedometer Head: Description and Operation
Circuit Operation
The Vehicle Speed Sensor produces voltage pulses of frequency proportional to vehicle speed. This signal is processed by the Vehicle Speed Sensor
Buffer (Diesel) or Vehicle Control Module (Gasoline) to produce a voltage pulse signal to the speedometer and odometer.