Removal and Replacement
Removing and installing wheel electronicsRemoving wheel electronics
General information on wheel electronics
The tyre pressure monitoring system (RDK) is designed to constantly monitor the tyre pressure during driving and when stationary. One set of electronics -A- per tyre is mounted in the rim well base. These measure tyre 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 tyre pressure has to be corrected.
There are two versions of the wheel electronics -A-. The standard version, including normal transmission power, is used in the 911 Carrera (997) (in the Cayenne, an amplified transmission power is deployed). These transmit on a high frequency range of:
^ 433 MHz or 315 MHz (special wheel electronics with 315 MHz have been developed for the Japanese market).
The following points can be used as distinguishing characteristics:
^ The labeling, 433 MHz or 315 MHz
^ The part number
^ Without 8 stars (the illustration shows 8 stars, 4 each to the left and right of the slot, wheel electronics with amplified transmission power from the Cayenne)
^ Special 315 MHz wheel electronics for Japan: identification with 14 oblique strokes (slashes)
^ And/or the colour (black 433 MHz/grey 315 MHz)
Removing wheel electronics
Note:
^ For vehicles with a tyre pressure monitoring system, the valve and wheel electronics are only replaced in exceptional cases! The following points can make replacement necessary!
Valve complete with screw -1 to 7- has to be replaced if:
^ The wheel electronics are removed
^ The self-locking -1- fastening screw is loose
^ The bead seat sealing ring -6- is porous or damaged
^ The valve body -7- is bent
^ The union nut -4- is loose.
The wheel electronics -A- must be replaced if:
^ The housing is visibly deformed
^ The filter surface (square, porous section on back of wheel electronics) is so badly soiled that it can no longer be cleaned by wiping
^ Tyre sealant (tyre sealing liquid) has been used
^ The service life of the battery has expired
^ There is a fault within the wheel electronics.
After removal of the tyre, the wheel electronics -A- can be seen at the valve in the outer rim well base.
1. Release wheel electronics from valve using a Torx socket screwdriver T 20 (if necessary, counter with a suitable assembly pin, e.g. steel pin 0 approximately 1.8 mm in bore at valve foot) and remove.
2. Then unscrew union nut and remove valve.
Installing wheel electronics
ATTENTION: The wheel electronics must not come into contact with the tyre fitting paste or solvent.
^ Do not apply compressed air, mounting paste, soap, solvents or any other cleaners to the wheel electronics when fitting/removing tyres.
When replacing the wheel electronics, always use a completely new valve and a new fastening screw!
The tightening torque for wheel electronics/valve is 4 Nm (3 ft lb.) ( 0.5 Nm/0.4 ft lb.)!
Every tyre set or wheel change must be communicated to the control unit. In particular, this includes the case where wheel positions have been interchanged. For this purpose, always select the tyre type and tyre size under Main menu > Tyre pressure > Adjustments in the instrument cluster. The control unit then learns the wheel positions again once the vehicle starts driving.
1. Install wheel electronics loosely at valve (do not tighten) and position in valve bore together with valve and bead seat sealing ring.
ATTENTION: Remove assembly pin after installing valve (required to counter). Otherwise the tyre will be damaged during installation.
^ Carry out the tightening procedure for the valve in one step (tighten without interruption the prescribed tightening torque is reached).
2. Position washer, chamfered on both sides, and screw union nut on as far as the mounting face. Visibly twist bore at valve foot. If necessary, block with suitable assembly pin. The tightening torque is 4 Nm ( 0,5 Nm) (3 ft lb. (0.4 ft lb.)).
3. Push wheel electronics -A- slightly into rim well (this adjusts the angle of inclination of valve to wheel electronics).
4. Carefully tighten self-locking (Torx) fastening screw T 20 to tightening torque 4 Nm ( 0.5 Nm (3 ft lb. ( 0.4 ft lb.)). The wheel electronics should now be lying evenly against the rim.