The ABS electronic anti-lock braking 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: If grip is lost, it helps to restore the vehicle to the correct trajectory. The most comprehensive versions of the ABS control unit also implements ESP (Electronic Stability Program) and ASR (Anti Slip Regulation) functions in addition to the HH "Hill Holder" function and the MSR function (adjustment of engine braking torque during gear change),The ESP system also acts on the motor and brakes to generate a stabilising torque when the ABS sensors detect conditions that cause the vehicle to slip. The ESP system has a specific sensor in addition to the ABS sensors: 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.With the Hill Holder function, a longitudinal acceleration sensor is also used that is built into the yaw sensor. The ESP system also uses information from the pressure sensor that measures pressure in the hydraulic circuit: this sensor is built into the hydraulic control unit.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 the slipping 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, the slipping is detected at one wheel only, the system cuts in to brake the slipping wheel only 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, right side.When the system is off, an LED in the button and a warning light in 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 torque is sufficient to start the vehicle comfortably.The Hill Holder is automatically activated when the brake pedal is pressed in conjunction with the following conditions: the vehicle speed equal to zero, the gradient more than 2% and the 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.For more details See descriptions 3350 TRACTION CONTROL ASR/ESP warning light: the warning light flashes when the system cuts in to notify 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 or HH function, it turns on the warning light in fixed mode.The control unit power supply lines are protected by two special fuses located in the engine compartment junction unit; the ignition-operated supply is protected by a specific fuse in the junction unit under the dashboard.