DTC P0500: Vehicle Speed Signal: Description
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The ECM receives vehicle speed over the Controller Area Network (CAN) from the Transmission Control Module (TCM) based on the output speed sensor. The output speed sensor is attached to the top rear of the transmission case. The sensor uses a hall effect switching device to transition from a low voltage to a high voltage as each of the eighteen teeth on the output shaft is passed. The ECM will continuously monitor the vehicle speed sent over the CAN link to verify the message is above a certain speed. DTC P0500 will set if the ECM does not detect a sufficient amount of vehicle speed from the TCM over the CAN link when engine speed is above a certain range with the transmission in fourth or fifth gear.