Download DTC P0500: VEHICLE SPEED SENSOR (VSS) MALFUNCTION (ES 300 & HIGHLANDER) CAUTION: If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. NOTE: For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS . Circuit Description Anti-Lock Brake System (ABS) wheel speed sensors detect wheel speed and sends signals to ABS ECU. The ABS ECU converts signals into a 4-pulse signal and outputs signal to instrument cluster. Instrument cluster converts signal to a more precise waveform and outputs signal to ECM. ECM determines vehicle speed based on frequency of these pulse signals. DTC is set when ECM does not detect any VSS signal while vehicle is in motion.