3310033 - E7022 VDC - Description

Description

The electronic anti-lock brake system (BOSCH 5.7 ABS with ASR) governs braking pressure sent to the wheels and prevents loss of grip under all tyre and road surface conditions.This is combined with a VDC (VEHICLE DYNAMIC CONTROL) system, which controls vehicle stability by modulating drive torque and braking the wheels differentially, if there is a loss of grip, thus helping to return the car to its correct trajectory.The VDC system acts on the engine and brakes to generate a stabilising torque when the ABS sensors detect conditions that could lead to the vehicle slipping.

The VDC system includes the following specific components over and above those of the ABS:

• a sensor which detects the steering wheel position (steering sensor);
• a sensor which detects the vehicle's rotation around the vertical axis and side acceleration (centrifugal force) (yaw sensor);
• a sensor that detects pressure on the hydraulic ABS unit (pressure sensor)

By processing information from the sensors, the control unit is able to find out car position moment by moment and compare the position with the driver's ideal trajectory. If the values do not tally, within a fraction of a second the control unit chooses and implements more effective actions to restore the vehicle to its trajectory immediately: it applies a braking force of different intensity to one or more wheels and reduces power transmitted by the engine if necessary.The VDC comes on automatically when the vehicle is started up and cannot be switched off.A warning light on the control panel flashes when the system cuts in to notify the driver that the VDC system has come on.VDC systems are always connected to ASR systems.The ASR system increases vehicle stability and active safety by controlling drive wheel slip. If slip is caused by excessive power transmission, it cuts in to reduce engine power through communication with the engine management control unit. if slip is detected at a single wheel, the system cuts in to brake the slipping wheel by acting on the modulation solenoid.ASR comes on automatically whenever the engine is started. The system can be deactivated by operating a button on the central console.When the system is off, a led on the button comes on at the same time as a warning light on the control panel.The ASR/VDC warning light flashes to notifiy the driver that the ASR system has cut in due to road surface grip conditions.When the control unit detects an error in the ASR function or the VDC function, it lights up the warning light constantly. As far as the ABS function is concerned,  See E7020  ABS . For further details see  Characteristic of working principle 3340  A(B.S. ANTI-LOCK BRAKING SYSTEM .)The supply lines to the control unit and the various system components (sensors and actuators) are protected by a specific maxifuse and by a fuse in the additional fuse box.The supply lines for the control unit and the various system components (sensors and actuators) are protected by two dedicated fuses located in the engine compartment control unit.