Function and control
Fig. 253 In the stowage compartment on the front passenger side: button for the tyre monitoring sys-tem.
l"'"""f'n First read and observe the Introductory l.-J,.:,LL Information and safety warnings & on page 318.
The tyre monitoring system uses data from the ASS sensors and other functions to check the speed of rotation and the rolling circumference of the individual wheels. The rolling circumference of the wheels changes, if the tyre pressure is too low. This is then shown by the tyre monitoring sys-tem ill in the instrument cluster.
The operation of the tyre monitoring system is im-paired:
• If the tyre pressure has been changed manual-ly.
• If the tyre has structural damage.
• If the vehicle Is loaded more heavily on one side.
• If the wheels on one axle are loaded more heavily, e.g. high load level.
• If snow chains have been fitted.
• If one wheel per axle has been changed.
• When driving with a heavy trailer attached.
• If you are driving under winter conditions or on unsurfaced roads.
• When driving fast with hard acceleration and braking manoeuvres.
Synchronising the tyre monitoring system
The tyre monitoring system will have to be re-synchronised after changing the tyre pressure, or after changing one or more wheels. This also ap-plies for changing the wheels, e.g. from the front to the rear, and for changing from summer tyres to winter tyres.
The saved values must be reset before the system can be resynchronised.
• Switch on the ignition, and while the vehicle is stationary
• Press and hold the =>Fig. 253 button until an acoustic confirmation signal is emitted.
• OR: with some vehicle equipment options, you can open menu option Tyre pressure in the in-strument cluster display and save the new tyre pressures there =>page 24.
Once the saved values have been reset, the sys-tem calibrates itself independently to the fitted tyres and the tyre pressures filled by the driver dur-ing normal vehicle operation. The calibrated values are adopted and monitored after a long journey at various speeds.
If the wheels are loaded more heavily than normal, e.g. if the vehicle is carrying heavy payload, the tyre pressure must be raised to the recommended full-load tyre pressure before synchronisation =>page 367.
m The tyre monitoring system stops working if l!.J there is a fault in the ESC or ASS =>page 269.
m When using snow chains, an incorrect dis-l!.J play may be shown as the snow chains in-crease the tyre circumference =>page 367.
Driver assist systems I 321
