Tire Pressure Monitoring Systems, commonly known as TPM systems, will soon be installed on most of the automobiles manufactured in the world. Most of these systems use a "direct" approach which incorporates the use of wheel based transmitters or sensors (typically incorporated into the valve stem).  These report tire pressure (in addition to the sensor ID) to the engine control module (ECM) or some specific controller module on the vehicle. For most of these vehicles, specifically those that use TPM position indicators on the instrument cluster or electronic vehicle information console (EVIC), each time that you rotate tires / wheels (or if a defective sensor is replaced) the TPM sensors must be retrained or reprogrammed in order to properly inform the driver of the correct vehicle location for a low or high pressure tire. If the receivers are not reprogrammed, the system will continue to report the correct pressures, but they will be reported in the wrong position on the vehicle information console or instrument cluster.