DTC P0500: Vehicle Speed Sensor "A" & DTC P0503: Vehicle Speed Sensor "A" Intermittent/Erratic/High: Notes
WARNING: This page is about a different car, the 2003 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
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, COMPUTER RELEARN PROCEDURES - LEXUS
article in GENERAL INFORMATION.