Active power brake booster, pedal pressure sensor (DSTC only)
The power brake booster is positioned on the firewall in the engine compartment. It consists of a vacuum cylinder (1), pedal position sensor (2), pressure build-up valve (3) and pedal pressure sensor (4).
The pedal pressure sensor is positioned in the power brake booster and provides the ABS control module with information about brake activity by the driver. If the driver depresses the brake pedal during traction control the control will stop.
The active power brake booster is controlled by the ABS control module and builds-up an initial brake pressure. This is so to allow braking during DSTC control. Initial brake pressure is built up within 100 ms of control starting. This occurs without the driver needing to depress the brake by opening the pressure build-up valve and allowing atmospheric pressure to enter the rear chamber. The brake pressure sensors (5) continuously monitor the brake pressure. The pulse width controlled pressure build up valve in the power brake booster maintains the pressure during DSTC control at around 10 bar.