Tire Monitoring System: Description and Operation

Tire Pressure Monitor Description and Operation
The Tire Pressure Monitor (TPM) system allows the driver to display all 4 tire pressures and the tire location on the Driver Information Center (DIC) wile the vehicle is being driven. The system uses the Remote Control Door Lock Receiver (RCDLR), DIC Dash Integration Module (DIM), Power Train Control Module (PCM), 4 Radio Frequency (RF) transmitting pressure sensors inside each wheel/tire assembly, and a class 2 serial data circuit to perform the system functions. When the vehicle is stationary for more then 15 minutes the sensors go into stationary mode. In this mode the sensors transmit once every 60 minutes, this minimizes sensor battery consumption. These batteries are not serviceable and require sensor replacement if low. As vehicle speed increases to 32 km/h (20 mph) centrifugal force closes the sensor's internal roll switch, causing the sensor to go into drive mode. In this mode the sensor transmits once every 60 seconds. The RCDLR translates the information within this RF transmission into tire location and tire pressure. The RCDLR sends this data to the DIC via a class 2 serial data circuit where tire location and their pressures are displayed. When the TPM system detects a tire pressure higher than 248 kPa (39 psi), or lower than 165 kPa (24 psi), the CHECK TIRE PRESSURE warning message is displayed on the DIC. When the DIC is scrolled to display the tire pressures additional messages are also displayed as follows, depending on that tire's pressure condition:
^ 172-262 kPa (25-38 psi) [TIRE OK]
^ 269 kPa (39 psi), or above [TIRE HIGH]
^ 165 kPa (24 psi), or below [TIRE LOW]
The TIRE HIGH, or TIRE LOW message can be cleared by adjusting tire pressures to the recommended kPa/psi. The sensor's pressure accuracy from -10° to 70°C (14° to 158°F) is plus or minus 14 kPa (2 psi). The TPM system can also compensate for high and low altitudes using the PCM's MAP sensor input via a class 2 serial data circuit. The RCDLR has the ability to detect malfunctions with in the TPM system. Any malfunctions detected will cause the DIC to display the SERVICE TIRE MONITOR warning message on the DIC.