The tire pressure monitor (TPM) system allows the driver to display all 4 tire pressures on the driver information center (DIC) while the vehicle is being driven. The system uses the remote control door lock receiver (RCDLR), body control module (BCM), powertrain control module (PCM), 4 radio frequency 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 than 20 minutes, the sensors go into power down mode. In this mode, the sensors transmit tire pressure data 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), the sensor's internal roll switches turn the sensors ON and they will each begin to transmit a unique identification code and a radio frequency signal. The RCDLR receives and translates this data into tire location and tire pressure. The RCDLR sends this data to the DIC via a class 2 serial data circuit where the tire pressures are displayed. If the TPM system detects a tire pressure above 289 kPa (42 psi), the HIGH TIRE PRESSURE warning message is displayed. If the system senses a tire pressure between 34-172 kPa (5-25 psi), the LOW TIRE PRESSURE warning message is displayed. And if the system senses below 34 kPa (5 psi), the FLAT TIRE warning message is displayed. After this message, 2 chimes will sound followed by the message MAX SPEED 55 MPH. The next message to appear is REDUCED HANDLING. The TPM system can also compensate for high and low altitudes using the PCM's barometric pressure sensor via a class 2 serial data circuit. The RCDLR 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. For more information on the RCDLR or remote function actuation (RFA) system, refer to Keyless Entry System Description and Operation .