Pressure sensor

Arrangement in vehicle

The pressure sensor is mounted on the boost piston unit in the output to the front axle circuit.

Connector assignments:

Measuring range and matching

The sensor supplies an analog signal with a measuring range from 0 to 250 bar.

The zero point is calibrated constantly after initialization of the system with "ignition ON" and is concluded after 100 ms provided the brake light switch is not operated.

Measuring principle

Steel diaphragm with piezo-resistive measuring principle based on the distortion of the diaphragm with subsequent conversion into a linear characteristic from 0 to 5 V.

Function in DSC3 system

• Assessment of model variables such as cornering force and brake force for all relevant driving conditions (brake not applies, partially applied, ABS control range).
  
• Evaluation of information in the ABS algorithm for the purpose of estimating the brake forces at the wheels.
  

Sensor break-away and short circuit detection

Monitoring with regard to plausible signal values by the DSC3 control unit in a time frame of 100 ms under following conditions:

• Signal interruption
  
• Short to positive
  
• Short to ground
  

Functional link with the brake light switch (BLS)

The following statuses are monitored by the electronic control:

When calibrated (zero calibration), the system pressure must not exceed 5 bar for a certain period of time provided the brake light switch is not operated.

The signals from the brake light switch (BLS) and pressure sensor are combined in the system and their sum forms a redundant BLS signal which in turn is monitored by the electronic control with regard to logic statuses.