K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Vehicle Speed Sensor Signal Buffer: Description and Operation
The Digital Ratio Adaptor Controller (DRAC) is a solid-state device that is used to change the signal from the speed sensor to a digital signal. The
DRAC is integral with the Instrument Cluster.
The DRAC is matched to the final drive and tire size of each vehicle. If the final drive or tire size is changed for any reason, the DRAC must be
recalibrated. Incorrect calibration will affect speedometer/odometer reading ,anti-lock brakes, engine control module, and cruise control module
