Tire Monitoring System: Description and Operation

TIRE PRESSURE MONITOR DESCRIPTION AND OPERATION
The Tire Pressure Monitor (TPM) System warns the driver when a significant loss of tire pressure occurs in any of the 4 tires and allows the driver to display the individual tire pressures and their locations on the driver information center (DIC) while the vehicle is being driven. The system uses the RFA antenna grid, antenna module, dash integration module (DIM), DIC, instrument panel cluster (IPC), 4 radio frequency (RF) transmitting pressure sensors inside each wheel/tire assembly, and the serial data circuit to perform the system functions. When vehicle speed is less than 32 km/h (20 mph), the sensors go into stationary mode. In this mode the sensors transmit to the antenna module through the RFA antenna grid once every 60 minutes to minimizes sensor battery consumption. As vehicle speed increases to 32 km/h (20 mph), centrifugal force close the sensor's internal roll switch causing the sensors to go into drive mode. In this mode the sensor transmits once every 60 seconds to the antenna module. The antenna module translates the data within the sensors RF transmission into sensor presence, sensor mode, and tire pressure. The antenna module then sends this information to the DIC via the serial data circuit where the tire pressures and there locations are displayed as follows:
XX PSI LF TIRE OK
XX PSI RF TIRE OK
XX PSI RR TIRE OK
XX PSI LR TIRE OK

If the TPM System detects a significant loss of tire pressure, the "CHECK TIRE PRESSURE" warning message is displayed on the DIC and the low tire pressure warning indicator is displayed on the IPC. Both the DIC message and the IPC indicator can be cleared by adjusting tire pressures to the recommended kPa/psi, refer to Tire Placard. The sensor's pressure accuracy from -10 to +70°C (+14 to +158°F) is plus or minus 7 kPa (1 psi). The antenna module has the ability to detect malfunctions within the TPM System. Any malfunctions detected will cause the DIC to display the "SERVICE TIRE MONITOR" warning message.