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, or gain of tire pressure occurs in any of the 4 tires and allows the driver to display all 4 tire pressures and the tire locations on the Driver Information Center (DIC) while 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 to minimizes sensor battery consumption. 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 to the RCDLR. The RCDLR translates the information within this RF transmission into sensor presence, sensor mode and tire pressure. The RCDLR sends the tire pressure information to the DIC via the serial data circuit where tire pressures and their locations are displayed. When the TPM system detects a significantly under inflated, or over inflated tire, 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:

"TIRE OK"
"TIRE HIGH"
"TIRE LOW"

The "CHECK TIRE PRESSURE", "TIRE HIGH", or "TIRE LOW" warning messages 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 the 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.