The Tire Pressure Monitor (TPM) system alerts the driver when a large change in tire pressure exists while the vehicle is being driven. The TPM system uses the Electronic Brake Control Module (EBCM), Antilock Brake System (ABS) wheel speed sensor inputs, class 2 serial data circuit, Systems monitor, or the Driver Information Center (DIC) (if equipped) 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 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 conditions. 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 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 EBCM turns on the TIRE PRESS indicator on the systems monitor. On vehicles equipped with a DIC the EBCM commands the DIC to display the CHECK TIRE PRESSURE waring message via a class 2 serial data circuit. The DIC message nor the Systems Monitor indicator appears if more than one tire pressure is high or low, or if the system is not properly calibrated. The system does not alert the driver to which tire pressure is high or low. If the tire pressures are at the specified psi the TIRE PRESSURE NORMAL message is displayed when selected on the DIC. To clear the TIRE PRESS indicator, or the CHECK TIRE PRESSURE message, refer to Tire Pressure Monitor Procedure .