RAM 2500 Truck 4WD V8-5.9L VIN Z LDC (1998)
Vehicle Speed Sensor: Description and Operation
The PCM uses a speed pulse input received from the Controller Anti-Lock Brake (CAB) and internal programming to decide what vehicle speed and
distance messages are required. The PCM then sends the proper messages to the instrument cluster circuitry on the CCD data bus. The CAB uses an
input from the rear wheel speed sensor and internal programming, which includes a programmable pinion factor to compensate for different axle gear
ratios and tire sizes, to determine what speed pulse output is required. The CAB then sends the proper speed pulse to the PCM on a hard-wired circuit.
