DTC P0500: Vehicle Speed Sensor Malfunction: Condition

WARNING: This page is about a different car, the 2002 Suzuki Esteem. However, it is still accessible from the selected car via links, so may be relevant.

DTC is set when Engine Control Module (ECM) does not detect Vehicle Speed Sensor (VSS) input voltage with vehicle decelerating in Drive. ECM continuously monitors this circuit. MIL is illuminated when ECM detects malfunction during 2 consecutive drive cycles. Possible causes are:

Short or open circuit between speedometer and ECM.
Speedometer driven gear malfunction.
ECM malfunction.
Speedometer malfunction.