Brake Vacuum-pressure Sensor
In both by-wire mode and conventional mode, a brake vacuum is required to reinforce the brake pressure. Therefore, the brake servo has a redundantly designed brake vacuum-pressure sensor. The SBA control unit uses these signals to continuously monitor the available brake vacuum. If the brake vacuum is too low, the electrical vacuum pump is activated. If the SBA control unit determines a fault in the brake vacuum supply, it sends a command to the digital motor electronics to start the combustion engine. When the combustion engine runs, the mechanical vacuum pump also works, thus ensuring the brake vacuum supply.
Take notes about sensors in and connectors at these units below.