Tire Monitoring System: Description and Operation
TIRE PRESSURE MONITORINGDESCRIPTION
This vehicle has a Tire Pressure Monitoring (TPM) system. It is there to alert the driver when air pressure in any of the vehicle's four tires falls below a predetermined threshold. It alerts the driver with a lamp in the instrument cluster.
The garage door opener/tire pressure monitor module (1) is located in the headliner near the inside rear view mirror (2). The TPM system utilizes a control module to control the system. The control module also has a garage door opener control module integrated along with it.
The tire pressure monitoring system utilizes transmitters that are located in the valve stem (1) of each tire (2) to communicate the tire pressure condition to the module. If a tire has low air pressure, an indicator light on the instrument cluster is illuminated. The vehicle operator must check the tire pressure of each tire in order to determine which tire has a low pressure condition.
The low tire pressure warning system utilizes these main components:
- Tire Pressure Monitoring Module
- Tire Pressure Sensors/Transmitters
- Tire Pressure Indicator Lamp
For information on specific components, refer to that individual component.
OPERATION
The Garage Door Opener/Tire Pressure Monitoring (TPM) module (1) has a microprocessor controller that can monitor the transmissions from the sensor/transmitters anytime the ignition is on. It can store the last 32 transmissions.
There are two important values included in these transmissions. They are:
- Why the transmission was sent
- Low Tire Pressure
The module compares the transmitted tire pressure from the sensor (2) to the two pressure thresholds (low pressure or critical pressure).
If the module determines that the tire pressure transmitted is below the low or critical pressure thresholds, it will signal for the "Low Tire" pressure warning lamp to come on.
The TPM module performs diagnostic routines, stores diagnostic trouble codes and provides the appropriate lamp status to the Body Control Module (BCM).
When the module determines there is a fault, the low tire pressure indicator lamp circuit is grounded and the BCM turns on the "Low Tire" pressure indicator lamp.
The TPM module also stores its own identification number, module version and the date of manufacture.