DTC P0503: Vehicle Speed Sensor Circuit Intermittent: Description
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
The Vehicle Speed Sensor (VSS) is a permanent magnet generator attached to the transmission case. The final drive assembly has a toothed wheel, VSS rotor. As the final drive assembly rotates, an AC voltage is induced and transmitted to the PCM. The PCM converts the AC voltage into a digital signal. The PCM uses vehicle speed to determine shift timing, torque converter clutch apply and release and gear ratio. If the PCM detects a loss of vehicle speed while the vehicle is in motion, then DTC P0503 sets.