312001147 - E7023 ESP - DESCRIPTION

DESCRIPTION

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: in cases of a loss of grip, it contributes to returning the vehicle to the correct path.The ABS control unit, in the fullest version, as well as the ESP function, also implements the A.S.R. (Anti Slip Regulation), Hill Holder, H.B.A. (Hydraulic Brake Assist) and M.S.R. (engine brake torque regulation in gear shifts reduction).The ESP system intervenes on the engine and on the brakes, producing a stabilizing torque when the ABS sensors detect conditions that could cause the vehicle to slip.The intervention of the system is signalled by the flashing of the warning light in the instrument panel to notify the driver that the car is in critical grip and stability conditions.

For the correct operation of the ESP and ASR systems it is vital that the tyres are the same make and the same type on all the wheels, in perfect condition and, above all, the recommended type, make and size.

The ESP system has a specific sensor in addition to those for the ABS: this yaw control unit detects vehicle rotation about the vertical axis and side acceleration (centrifugal force); it also uses steering sensor signals from the electric steering control unit supplied via the CAN.A longitudinal acceleration sensor is also provided with the Hill Holder function, incorporated into the same yaw control unit. In 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.

Following sharp braking which causes a substantial deceleration, the Body Computer activates the emergency lights having received the car speed signal from the ABS control unit. When this deceleration value drops below a pre-set threshold, the hazard function is automatically deactivated.

    See E2020 DIRECTION INDICATORS / HAZARD WARNING LIGHTS 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 panel controls in the centre of the dashboard. 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 MSR system (engine drive regulator) is an integral part of the ASR, which intervenes if there is a sudden change to a lower gear, by supplying torque to the engine, thereby preventing excessive drive at the drive wheels which, especially in poor grip conditions, could lead to a loss in stability of the vehicle.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 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 other conditions being equal, the Hill Holder keeps the braking system pressurized for 2 seconds to allow the driver to move his/her foot from the brake pedal to the accelerator pedal without the vehicle slipping backwards and without using the parking brake.When 2 seconds have elapsed, with no departure having taken place, the system is automatically deactivated, gradually releasing the braking pressure. During this release stage it is possible to hear a typical mechanical brake release noise, indicating the imminent move of the car.The HH is not activated with reverse gear engaged.If there is a problem with the ESP system / ASR / Hill Holder it is automatically switched off and the warning light in the instrument panel comes on constantly together with a message in the display, where present.The direct battery power supply line from the control unit (pump and solenoid) is protected by two fuses located in the engine compartment junction unit; the ignition-operated power supply is also protected via a fuse.