Operation

OPERATION

Each Tire Pressure Sensor/Transmitter serves three functions:

- It is used as a valve stem to inflate and deflate the tire.
- It periodically measures tire pressure. (Approximately every 30 seconds.)
- It transmits the tire pressure value to the Tire Pressure Monitor (TPM) module in the vehicle. (Approximately every 60 seconds or if tire pressure changes by one psi or more between transmissions.)

The system operates by monitoring a radio frequency transmission from the sensor/transmitters located in each wheel. When the vehicle reaches a speed of approximately 32 km/h (20 MPH), centrifugal force created by the rotating wheels closes a roll switch inside each sensor/transmitter, powering up the circuitry.

The Tire Sensor/Transmitters will only send out information when vehicle speed is above 32 km/h (20 MPH). To facilitate transmitting the radio signal to the TPM module, the valve stem acts as the antenna for the tire pressure sensor/transmitter. When the TPM module senses tire pressure is below the calibrated threshold, the TPM system will illuminate the "Low Tire" pressure indicator lamp in the Instrument Cluster.

The Tire Pressure Sensor/Transmitter is powered by an internal battery. The battery is not replaceable separately. In the event of battery failure, the entire Tire Pressure Sensor/Transmitter at that wheel will require replacement. To extend the life of the battery, the sensor/transmitter is not activated until the vehicle reaches a speed of approximately 32 km/h (20 MPH) as stated earlier.

Each Tire Pressure Sensor/Transmitter has a unique identity code. This will allow the TPM system to indicate to a technician, through Diagnostic Trouble Codes (DTCs) in the module, which sensor/transmitter of the vehicle is faulty. For this reason, if a Tire Pressure Sensor/Transmitter needs to be replaced, all the Tire Pressure Sensors/Transmitters must be relearned to the TPM module.