1.3.6. The air pressure control system in tires

The air pressure control system in tires controls pressure of air of four driving wheels during the movement.

Fire of the corresponding symbols and conclusion of text indication to the display of a combination of devices the system warns the driver about pressure drop of air in tires. Some modifications of the car are completed with the multi-color display with the increased resolution. The system works with the help of the sensors mounted on wheels. Radio signals of these sensors come to the air pressure control system in tires.

It is necessary to remember that air pressure in tires also depends on tire temperature. With temperature increase of the tire on 10 °C air pressure in it increases approximately by 0,1 bars. During the movement the tire heats up and as a result air pressure increases. Therefore it is possible to correct air pressure only on cold tires when tire temperature approximately corresponds to surrounding temperature.

Regular control, adjustment if necessary and input in memory of the set air pressure in tires is necessary for trouble-free function of the control system of pressure of air in tires.

Norms of pressure of air in tires it is possible find in the plate pasted on a door rack.

NOTE The underestimated air pressure in tires increases fuel consumption and accelerates wear of tires. When replacing tires it is not allowed to remove or change sensors and gates. It is necessary to replace only a gate zolotnik. Change the gate and electronics of a wheel only if necessary.

At big loss of pressure of air the red symbol appears.

Fig. 1.67. An alarm symbol with text indication

Emergence of a symbol on the display means pressure drop of air in the tire of at least one wheel. In this case it is necessary to stop and check tires/tires.

If necessary replace a wheel.

If pressure drop of air concerning the set pressure makes more than 0,5 bars, on the display the symbol together with text indication appears: "Reifendriicke priifen"

NOTE In case of a car complete set PAX system under certain conditions perhaps further movement. In case of deliberate deflation of air from a wheel, for example, at adjustment of pressure, new pressure should be programmed anew.

At moderate loss of pressure of air the yellow symbol appears.

Fig. 1.68. Indication of moderate loss of pressure of air

If pressure drop of air concerning the set pressure makes more than 0,3 bars, on the display the tire symbol appears.

NOTE It is allowed to correct air pressure in tires only when temperature of tires approximately corresponds to surrounding temperature.

The correct input in memory of the set pressure is the main condition of accuracy of function of the control system of pressure of air in tires.

Fig. 1.69. Input in memory of pressure of air

Air pressure control system accuracy condition in tires is input in memory of the set air pressure at each adjustment of pressure, for example, in case of change of loading of the car (fig. 1.69). For functioning of the control system of pressure of air in tires it is necessary to modify air pressure.

Check air pressure in tires.

If necessary modify pressure according to the norms given in the door pasted on a rack to the plate.

Enter these pressure of air into memory

Press the RESET button mounted on the screen wiper handle.

You will choose "Reifendruck-Kontrollsystem".

You will choose "Reifendruck speichern".

Input in memory of data of pressure of air is necessary every time after deliberate change of the set pressure.

After input in memory the air pressure control system measures actual data of pressure of air in tires and enters them into memory as the new set pressure.

In case of replacement of a wheel it is necessary to program these pressure of the replaced wheels anew.

Press the RESET button mounted on the screen wiper handle.

You will choose "Reifendruck-Kontrollsystem".

Fig. 1.70. Radwechsel menu (replacement of a wheel)

You will choose "Radwechsel" (replacement of a wheel) (fig. 1.70).

In case of replacement of a wheel realization of the Radwechsel function (replacement of a wheel) is required. After selection of function there is a programming of values of pressure of new wheels. This stage of programming can last up to twenty minutes.

At a programming stage operability of system is limited. It means that alarm indication is possible only at air pressure drop below of minimum admissible set pressure in one or several wheels. In this case there is a red alarm symbol with text indication of "Reifendruck" (air pressure in tires).

Functional violation can be caused by various reasons.

Fig. 1.71. Malfunction indication

In the absence of access to system on the display there is a crossed-out symbol of the tire (fig. 1.71).

Emergence of this symbol at the end of process of programming can mean that the system does not identify the wheels mounted on the car. The reason can consist in installation of one or several wheels without sensor.

It can also mean failure of a sensor of a wheel or other components.

The system identifies more than 4 wheels of the car, for example, when transporting in the car of winter wheels.

Replacement of a wheel was carried out without inclusion of the Radwechsel function (replacement of a wheel).

At operation of chains of antisliding, owing to properties of shielding of chains, malfunction of system can take place.

Sending devices with an identical frequency, for example, the earphones or radio stations which are in the car can be owing to strong electromagnetic fields the reason of temporary malfunction of system.

Eliminate whenever possible malfunction and in conclusion once again cause the Radwechsel function (replacement of a wheel).