Circuit Description

Speed sensor circuit consists of a magnetic, induction-type sensor, vehicle speed sensor buffer/module and wiring. Gear teeth pressed on output shaft induce an alternating current in sensor. Signal is transmitted to buffer. Buffer compensates for various axle ratios and converts signal into a square wave for use by speedometer, cruise control, anti-lock brakes and PCM. Buffer sends 2 different signals to PCM.

DTC will set when the following conditions are present:

Vehicle speed is greater than 20 MPH.
Four wheel low is not selected.
VSS buffer calculated speed is less than half transmission calculated speed.

VSS buffer calculated speed is greater than transmission calculated speed by 20 MPH.
Conditions are met for 2 seconds.