General Information On Wheel Electronics
The tire pressure monitoring (TPM) system is designed to constantly monitor the tire pressure during driving and when the vehicle is stopped. One set of wheel electronics -A- per wheel is mounted in the rim well base. These measure tire pressure and temperature at regular intervals and transfer the values to a central control unit via a high-frequency route. The control unit 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 needs to be adjusted.
There are two versions of the wheel electronics -A- . Wheel electronics with normal transmission power are used on the Boxster (987) (while the version on the Cayenne has amplified transmission power). These transmit on a high frequency range of:
- 433 MHz or 315 MHz (while special wheel electronics with a frequency of 315 MHz are used for Japan).
The following points can be used as distinguishing characteristics:
- the labelling, 433 MHz or 315 MHz
- the part number
- without 8 stars (figure shows 8 stars, four on the left and right of the slot respectively, wheel electronics with amplified transmission power on the Cayenne)
- special wheel electronics - 315 MHz for Japan: marking with 14 diagonal lines
- and/or the color (black = 433 MHz/grey = 315 MHz).
-A- - Wheel electronics
-B- - Valve complete (No. 2 to No. 7)
-1- - Self-locking (Torx) fastening screw
-2- - Valve cap (plastic)
-3- - Valve insert
-4- - Union nut
-5- - Washer chamfered on both sides
-6- - Bead seat sealing ring
-7- - Valve