Tire Monitoring System: Description and Operation

TIRE PRESSURE MONITORING (TPM)






DESCRIPTION

This vehicle has a tire pressure monitoring (TPM) system as standard equipment. It is there to alert the driver when air pressure in any of the vehicle's four tires falls below a predetermined threshold or if there is a failure in one of the TPM components. TPM alerts the driver with "LO TIRE" displayed in the cluster odometer and an audible chime tone.


The TPM system utilizes these main components:

- Tire Pressure Monitoring Module
- Tire Pressure Sensor/Transmitters (Four - One in each wheel)
- Cluster Odometer Message LO TIRE
- Body Control Module (communication link)


OPERATION

The Tire Pressure Monitoring (TPM) system operates by monitoring a radio frequency transmission from the tire pressure sensor/transmitters located in each wheel, and integrated with the valve stem. When the vehicle reaches a speed of approximately 32 km/h (20 mph), centrifugal force created by the wheels rotating closes a roll switch inside each sensor, powering up the circuitry. To facilitate transmitting the radio signal to the TPM module, the valve stem acts as the antenna for the tire pressure sensor/transmitter.


The Body Control Module (BCM) monitors the tire pressure signal that is sent from the TPM module when the ignition key is in RUN/START position. When the BCM receives the tire pressure signal it will send a corresponding bus message to the cluster. If the BCM message indicates a fault, then the cluster will display in the odometer "LO TIRE" and send a chime request message to the BCM.