The Tire Pressure Monitor (TPM) System warns the driver when any one, or all of the vehicles tire pressures have become significantly under, or over inflated. The system also allows the driver to display the individual tire pressure on the driver information center (DIC).
The system uses the powertrain control module (PCM), body control module (BCM), instrument panel cluster (IPC), DIC, remote control door lock receiver (RCDLR), a radio frequency (RF) transmitting pressure sensor in each wheel/tire assembly, and the serial data circuit to perform the system functions.
When the vehicle is stationary for 15 minutes the sensors go into a stationary mode. In this mode the sensors sample tire pressure once every 15 minutes and transmit in stationary mode once every 60 minutes. As vehicle speed increases, centrifugal force closes the sensors internal roll switches, which puts the sensors into drive mode. In this mode the sensors sample tire pressure once every 10 seconds and transmit in drive mode once every 60 seconds. The RCDLR receives and translates the data contained in each sensors RF transmission into sensor presence, sensor mode, and tire pressure. The RCDLR then sends the tire pressure data to the DIC via the serial data circuit where they are displayed as follows:
| • | FRONT L XX R XX PSI |
| • | REAR L XX R XX PSI |
The sensors compare their current pressure sample with their last transmitted pressure and will transmit in re-measure mode whenever an 8.2 kPa (1.2 psi) change in tire pressure has occurred. When the TPM system detects a significantly under inflated tire pressure, the IPC displays the low tire pressure indicator and the DIC displays the following messages:
| • | LOW TIRE PRESSURE XX |
| • | XX TIRE FLAT - MAX SPEED 55 MPH - REDUCED HANDLING |
When the system detects a significantly over inflated tire pressure the HIGH TIRE PRESSURE XX message is displayed on the DIC. Both the messages and indicator can be cleared by adjusting the tire pressures to the recommended kPa/psi. Refer to Tire Placard in General Information, or to Tire Inflation Pressure Specifications in Maintenance and lubrication. The sensors pressure accuracy from -10 to +70°C is +/- 14 kPa (2 psi). The system also compensates for changes in barometric pressure using the PCMs map sensor via the serial data circuit.
The RCDLR has the ability to detect malfunctions within the TPM System. Any malfunction detected will cause the DIC to display the SERVICE TIRE MON SYS message. For more information on other functions of the RCDLR, refer to Keyless Entry System Description and Operation in Keyless Entry.
