Tire Pressure Monitor Description and Operation Domestic and Europe Export

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 individual tire pressures to be displayed on the DIC.

The system uses the powertrain control module (PCM), body control module (BCM), remote control door lock receiver (RCDLR), instrument panel cluster (IPC), DIC, a radio frequency (RF) transmitting pressure sensor inside each wheel/tire assembly, and the 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 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 causing the sensors to go 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 sensor's RF transmission into sensor presents, 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:

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:

When the TPM system detects a significantly over inflated tire pressure, the DIC displays the HIGH TIRE PRESS XX message. Both the messages and indicator can be cleared by adjusting the tire pressures to the recommended kPa/psi. Refer to Tire Inflation Pressure Specifications in Maintenance and Lubrication or to Tire Placard in General Information. 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 also compensates for changes in barometric pressure using the PCMs barometric pressure 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 SVC TIRE MONITOR message. For more information on other functions of the RCDLR, refer to Keyless Entry System Description and Operation in Keyless Entry, Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent and to Vehicle Theft Deterrent (VTD) Description and Operation in Theft Deterrent.

Tire Pressure Monitor Description and Operation Japan Export Only

The tire pressure monitor (TPM) system alerts the driver when a large change in the pressure of one tire exists, while the vehicle is being driven. The TPM system uses the electronic brake control module (EBCM), ABS wheel speed sensor inputs, the GMLAN serial data circuit, and the driver information center (DIC) to perform the system functions. The EBCM contains software to calculate relative tire pressure differences. The software requires approximately 30 minutes of straight line driving in each of the three different speed ranges to complete the calibration process to have full capability for detecting a tire pressure condition. The speed ranges are as follows:

Each speed range has 2 modes of tire pressure detection:

The EBCM learns the tire pressure calibration for each speed range independently. In Monitor Mode 1, the EBCM has only partially learned the tire pressure calibration for the speed range and has limited detection capability for a tire pressure condition. In Monitor Mode 2, the EBCM has fully learned the tire pressure calibration for the speed range and has full detection capability for a tire pressure condition. Once the TPM system has fully learned the tire pressure calibration the EBCM monitors the ABS wheel speed sensor inputs, which will all be the same as the learned calibration if the tire pressures stay the same. If the tire pressure increases or decreases in one tire so to will that tires circumference and radius, which causes that wheel speed sensor input to change. The EBCM recognizes this change in wheel speed as a tire pressure condition. If the pressure in one tire becomes at least 69 kPa (10 psi) higher or lower than the other three the DIC will display the CHECK TIRE PRESSURE warning message via the GMLAN serial data circuit. This message does not appear if more than one tire is high or low, or if the system is not at least partially calibrated. The system does not alert the driver to which tire is high or low. If the tire pressures are at the specified kPa/psi the TIRE PRESSURE NORMAL message is displayed when selected on the DIC. To clear the CHECK TIRE PRESSURE warning message refer to Tire Pressure Monitor Procedure .