The tire pressure monitor (TPM) system is a software driven system. The system uses the existing antilock braking system components (electronic brake control module (EBCM) and wheel speed sensors), class 2 serial data messages, and instrument cluster to perform the system functions.
The EBCM contains the software to perform the system monitoring functions. The EBCM uses wheel speed data obtained from the wheel speed sensors to detect relative rotational differences due to low tire pressure. This means that one tire is at least 82 kPa (12 psi) lower in pressure than the other three. Braking, an acceleration or deceleration of greater than 0.1 g, and/or any ABS/TCS system activity causes the EBCM to temporarily suspend the tire inflation monitor system functions. When the EBCM detects a low tire pressure condition, the EBCM sets DTC B2818 Low Tire Pressure System Reset Circuit Low or DTC C1245 Low Tire Pressure Detected and sends a message to the instrument cluster via the class 2 serial data line.
The instrument cluster performs two functions related to the tire monitoring system.
| • | Displays the warning message LOW TIRE when commanded by the EBCM, via the class 2 serial data message. |
| • | Sends the tire inflation monitor system reset command to the EBCM, via the class 2 serial data line. |
The class 2 serial data line is used to send all tire pressure monitor system related information between the EBCM, BCM and the instrument cluster.
