Only vehicles equipped with antilock brakes (JM4) may be equipped with tire pressure monitoring (TPM). Refer to Service Part Identification Label in General Information or ABS Description and Operation in Antilock Brake System to determine if the vehicle is equipped with antilock brakes (Pontiac only). Antilock brakes are standard equipment on Oldsmobile, and JM4 will not appear on the RPO label. If the vehicle has antilock brakes, to determine if the vehicle also has TPM, perform a bulb check by turning the ignition ON. Refer to Instrument Cluster Description and Operation in Instrument Panel, Gages, and Console. If the LOW TIRE PRESSURE indicator illuminates, then the vehicle has TPM. If the LOW TIRE PRESSURE indicator does not illuminate, perform a bulb check using the scan tool to verify that the bulb is not inoperative. If the bulb illuminates when commanded by the scan tool, but does not illuminate when performing a bulb check using the ignition switch, then the vehicle does not have TPM.

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), antilock brake system (ABS) wheel speed sensor inputs, class 2 serial data circuit, and the instument panel cluster (IPC) 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 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 EBCM commands the IPC to turn on the LOW TIRE PRESSURE indicator via a class 2 serial data circuit. This indicator does not appear if more than one tire is high or low, or if the system is not properly calibrated. The system does not alert the driver to which tire is high or low. To turn off the LOW TIRE PRESSURE indicator, refer to Tire Pressure Monitor Procedure .