Tire Defect Indicator (RPA)
The RPA function is integrated in the DSC control unit. The system compares by way of the wheel speeds the tire-tread circumferences of the 4 wheels.
The RPA system does not monitor the uniform diffusion loss over all 4 tires. If the same pressure loss occurs in the 4 tires, the wheel speeds change to the same extent and the pressure loss is not detected. The customers must regularly monitor inflation pressures themselves.
The system must be re-initialized when tire inflation pressures are changed or when the tires are changed. The RPA is initialized by means of the controller at terminal 15 ON. The system switches to the "Learning phase" status. This status is shown in a status line in the Central Information Display (CID). After a brief driving time, the system learns the new wheel speeds as reference values.
For the RPA there are 2 variable warning lamps with 2 associated Check Control messages (CC messages) which are displayed in the instrument cluster:
- "Tire puncture!" signals a loss of pressure of more than 30% in a tire. This is accompanied by a gong sound.
- "Run Flat Indicator failure!" signals that the system is inactive due to a fault and can not detect any tire failures.
Explanatory notes pertaining to the relevant CC messages appear in the CID.
The RPA submenu in the CID also features a status line which indicates the current RPA status.
- "Learning phase," i.e. the system is standardized. The learning phase is indicated until RPA is ready for operation the first time after the start of standardization.
- "Inactive" because there is a fault in the system and thus no tire failure can be detected.
- "Active" when the system can detect a tire failure.