Vehicle Speed Sensor Signal Buffer: Description and Operation

The Vehicle Speed Sensor (VSS) is a gear-driven permanent magnet generator housed in the vehicle's transmission. The sensor produces a sine-wave output with a frequency proportional to vehicle speed. Twisted pair PPL/WHT (821) and LT GRY/BLK (822) wires deliver this signal to the Vehicle Speed Sensor Buffer. The Vehicle Speed Sensor Buffer converts this signal to an output signal which is switched to ground at a frequency of 4000 pulses per mile. This output is ported to the DK GRN/WHT (817) wire, to the DK GRN (389) wire, and to the WHT (696) wire. The Radio output is used to produce speed compensated volume (Refer to Radio/Stereo). Radio, Stereo, and Compact Disc
The Instrument Cluster output is used to generate speedometer and odometer indications (Refer to Instrument Cluster). This signal is also used by the Powertrain Control Module. A second output at 40 pulses-per-revolution output is provided at the BRN (437) wire for use in the Powertrain Control Module. The Powertrain Control Module uses these signals for control of Torque Converter Clutch (TCC), shift solenoids, and cruise control operations. A final output to the Four Wheel Antilock Brake System (ABS) is ported to the WHT (696) wire for use by the ABS System.