The BOSCH 8.0 ABS electronic ant-ilock braking system and wheel slip system regulates the braking pressure transmitted to the wheels, preventing them from losing grip whatever the tyre and road conditions.It is linked to the ESP (Electronic Stability Program) system which controls the stability of the vehicle, intervening, if necessary, on the drive torque and braking the wheels in a differentiated manner: in cases of a loss of grip, it contributes to returning the vehicle to the correct path.On the most extensive version the ABS control unit also implements the ESP (Electronic Stability Program) and ASR (Anti-Slip Regulation) functions plus the HH Hill Holder function and HBA (Hydraulic Brake Assist) function.The ESP system intervenes on the engine and on the brakes producing a stabilizing torque when the ABS sensors detect conditions that could lead to the vehicle slipping.The ESP system has a specific sensor in addition to those for the ABS: this sensor detects vehicle rotation about the vertical axis and side acceleration (centrifugal force) (yaw sensor); it also uses steering sensor signals from the electric steering control unit supplied via the CAN.A longitudinal acceleration sensor is also adopted for the HH functionIn addition, the ESP system uses the information for the pressure sensor which measures the pressure in the hydraulic circuit: this sensor is built into the hydraulic control unit.The H.B.A. system aids the driver in emergency braking situations when the brake pedal is activated quickly and in poor load maintenance conditions; the system intervenes when the pressure gradient exceeds a certain level (fast application of brake pedal - emergency braking) multiplying the braking pressure at the wheels applied by the driver thereby producing the maximum deceleration that can be achieved.The ESP system is always combined with the ASR system.The ASR system increases the active safety and stability of the vehicle controlling the slipping of the drive wheels: if slip is caused by the transmission of excessive power, the system cuts in, with the co-operation of the engine management control unit, to reduce engine power output. If, on the other hand, slip is detected at one wheel only, the system cuts in to brake only the slipping wheel by means of the wheel''s modulating solenoid valve.The ASR comes on automatically whenever the engine is started: the system can be switched off using the "ASR OFF) button located in the controls in the centre of the dashboard.When the system is off, an LED on the button and a warning light on the control panel come on simultaneously . The ESP function, on the other hand, is switched on automatically each time the engine is started up and cannot be turned off.The Hill Holder system is designed to assist the driver when setting off on an incline. In effect the HH is capable of automatically providing sufficient braking torque to keep the vehicle stationary until the clutch is fully released and the engine toruqe is sufficient to start the vehicle comfortably.The HH is automatically activated when the brake pedal is pressed in conjunction with the following conditions: vehicle speed equal to zero, gradient more than 2% and clutch pedal pressed.The moment the brake pedal is released, with all the other conditions being equal, the Hill Holder keeps the braking system pressurized for 2 seconds to allow the driver to move their foot from the brake pedal to the accelerator pedal without the vehicle slipping backwards and without using the parking brake.Once the accelerator is pressed, the Hill Holder continues to keep the vehicle still for a further 10 seconds or until the engine torque is sufficient to start the vehicle.The HH Is not activated with reverse gear engaged.ASR/ESP warning light: the warning light flashes when the system cuts in to notifiy the driver that the ASR has come on due to road grip conditions.When the control unit detects an error in the ASR or ESP function, it turns on the warning light in fixed mode.HH warning light: when the control unit detects an error in the HH function, it turns on the warning light in fixed mode.As far as the ABS function only is concerned, See E7020 ABS.For more details See descriptions 3350 TRACTION CONTROL.