Tire Monitoring System: Description and Operation

General information on the tire pressure monitoring system

There are two versions of the wheel electronics. In the case of the Cayenne, versions with amplified transmitting power are used. These transmit in the high frequency range:
- 433 MHz or 315 MHz.

The following points can be used as distinguishing characteristics:
- The labelling, 433 MHz or 315 MHz
- The part number
- 4 stars on left and right of the slot (wheel electronics with amplified transmitting power only)
- And/or the colour (dark grey 433 MHz; light grey 315 MHz).

The tire pressure monitoring system is designed to constantly monitor the tire pressure when the car is moving and stationary. One set of electronics per tire is mounted in the rim well base. The wheel electronic component sends its own identification number approximately once every minute regarding wheel position detection, the status of the battery service life, the currently measured wheel pressure and tire temperature to an antenna that is fitted in the wheel housing. This antenna measures tire pressure and temperature at regular intervals and transfers the values to a central control module via a high-frequency route. The control module evaluates the information and transfers the data to the instrument cluster if required. In this way, the driver is warned and informed if the tire pressure has to be corrected.

If the tire pressure drops by more than 0.2 bar per minute, the wheel electronics switch to fast transmission mode for 280 seconds and transmit the signals mentioned each second.

This system has a number of advantages:

Safety
^ Early warning in the event of a gradual loss of tire pressure.
^ If there is a severe drop in pressure, the driver is warned immediately, the wheel electronics switch to fast transmission mode.
^ Immediate warning in the event of a severe drop in pressure when the vehicle is stationary (tire failure).

Convenience
^ Still only a tire pressure check if it appears in the display in the instrument cluster.

Service life of the tires
^ Tire wear is minimized because the air pressure is always correct.
^ Fuel consumption is reduced.

Service life of the wheel electronics during storage
^ The wheel electronics are in an idle state when stored. This means that they do not transmit any signals.
^ The wheel electronics are only activated (only transmit) once they have been subjected to an air overpressure of at least 2 bar over a period of two minutes. Up to this point, the service life is higher than in the activated operating state (approximately 4 - 7 years).