Circuit Description
WARNING: This page is about a different car, the 2002 GMC Sonoma and 2002 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The vehicle speed sensor (VSS) assembly provides vehicle speed information to the powertrain control module (PCM). The VSS assembly is a permanent magnet generator. The VSS produces alternating current (AC) as the rotor teeth on the output shaft of the transmission pass through the magnetic field of the sensor. The frequency and amplitude of the AC waveform both increase as vehicle speed increases.
If the PCM detects no vehicle speed for a specified length of time while other sensors indicate that the vehicle is moving, DTC P0502 sets. DTC P0502 is a type A DTC.