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. The ABS system is linked to the ESP (Electronic Stability Program) system which controls the stability of the vehicle and intervenes, if necessary, on the drive torque, braking the wheels in a differentiated manner: if grip is lost the ABS helps to return the vehicle to the correct path. The ABS control unit, in the most comprehensive 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 during downshifting). The ESP system intervenes on the engine and on the brakes, producing a stabilising torque when the ABS sensors detect conditions that could cause the vehicle to slip. A flashing warning light in the instrument cluster signals that the system has intervened and notifies the driver that the car is in critical grip and stability conditions. ATTENTION: For correct operation of the ESP and ASR systems it is vital that the tyres are the same make and the same type on all wheels and that they are 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: a 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 which is incorporated into the same yaw control unit. The ESP system also uses the information from the pressure sensor which measures 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). This multiplies the braking pressure at the wheels applied by the driver, thereby producing the maximum deceleration that can be achieved. NOTE: Following sharp braking which causes considerable deceleration, the Body Computer receives the vehicle speed signal from the ABS control unit and activates the hazard warning lights. When this deceleration value goes below a pre-set level, the hazard function is automatically deactivated

See: DIRECTION INDICATORS / HAZARD WARNING LIGHTS (Container)

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 transmission of excessive power causes slip, 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 is automatically activated 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 automatically activated 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 of vehicle stability.

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 depressed, 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 pressurised 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 the system is automatically deactivated and gradually releases the braking pressure without any departure having taken place. During this release stage you may hear a typical mechanical brake release noise. This indicates that the car is about to move.

The HH is not activated when reverse gear is engaged.

If there are any faults in the ESP / ASR system it will automatically disengage. The relevant warning light will come on in the instrument cluster and a message will be shown on the display. At the same time, the Hill Holder device fault will activate the relevant warning light.

The direct battery supply lines for the control unit (pump and solenoid valves) are protected by two dedicated fuses located in the engine compartment junction unit. The ignition-operated power supply is protected in the same way by a dedicated fuse.