Two different tyre pressure monitoring systems are used on the Astra-H.
DDS
The DDS is a function of the ABS MK60 ESP and calculates the pressure loss in the tyres via the wheel speed sensors of the ABS. When the vehicle is being driven, the speed of each wheel is monitored continually. Loss of pressure in the tyre reduces the tyre's diameter and thereby the rotational speed of the wheel. If the system detects a difference in rotational speed such as this, the control indicator (red) will light up. The DDS is an indirect measurement system as it only gives a warning about loss of air but does not say which tyre/wheel is affected.
The control indicator lights up when there is a pressure deviation of approx. 30% compared with the other tyres. If there is a fault in the system, the (yellow) control indicator lights up.
TPMS
The tyre pressure monitoring system (TPMS) is a direct measuring system which works together with the DDS. Four pressure and heat sensors located in the tyres continually monitor the inflation pressure whilst the vehicle is being driven. The air/inflation pressure is transmitted by radio wave directly to the TPMS control unit (which is also a receiver). In contrast to the Vectra-C, the TPMS on the Astra-H only works with one receiver (TPMS control unit). All signals received (pressure, heat) are first evaluated by the TPMS control unit and transmitted on the CAN bus via the ABS control unit to the instrument cluster.
The current tyre inflation pressures can be read from the Info Display.
If the system detects that there is a pressure difference in one or more tyres, an indicator appears in the Info Display showing the position of the faulty tyre. Pressure differences down to 0.1 bar can be displayed.
For the system to work, all wheels have to be fitted with pressure sensors, all tyres have to be inflated to the specified air pressure and the system has to be initialised.
The tyre pressure monitoring system is ready to operate once the ignition is on and continually checks the tyre pressure once the vehicle has reached a speed of 30 km/h.
The DDS operates together with the TPMS and serves as a back-up system should one or all of the tyre pressure sensors fail. The DDS system indicates a deviation in air pressure or a system fault by means of a control indicator in the instrument panel:
- Yellow display, system fault
- Red display, deviation in tyre pressure
Note: The spare wheel is not fitted with a tyre pressure sensor.
Should there be a deviation in tyre pressure, the TPMS displays the following messages in the Info Display along with the current measurements for the individual tyres:
- Slight pressure deviation: Display reads "Check rear left tyre pressure"
- Large pressure deviation: Display reads "Warning! Pressure loss in left rear tyre"
If there is a fault with one or all of the tyre pressure sensors, the TPMS operation automatically switches to the DDS system of the ABS. It calculates the pressures automatically from a speed of approx. 30 km/h by means of the wheel speed sensors.
Vehicles with tyre pressure monitoring systems can be recognised by the fact that the tyre valve stems are made of metal and have aluminium caps, instead of the usual rubber stems and plastic caps.
In the event of a puncture, do not use liquid tyre repair systems as they will damage the tyre pressure sensors.
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