244007338 - E7020 DESCRIPTION OF ABS

Description

The electronic antilock braking system regulates the braking pressure transmitted to the wheels, preventing them from losing grip whatever the tyre and road conditions.The system is designed to complement the conventional mechanical braking system and not to replace it, thereby guaranteeing effective safety in the case of problems: the system operates using the same brake fluid as in the conventional mechanical brake circuit.Four sensors, located on each of the four wheels, indicatae the speed of each wheel to the electronic control unit, recording any situations involving locking, slipping or loss of grip.If these situations occur, the electronic control unit operates solenoid valves, which modulate pressure in the hydraulic circuit to prevent lock and restore the vehicle to permissible grip limits to ensure the shortest possible stopping distance without losing control of the steering.Two regulation solenoids are fitted (a pressure charge solenoid and a pressure discharge solenoid) for each wheel.The sensors are active type, i.e. they consist of a receiver that faces a magnetic encoder built into in the hub bearing: under these conditions, the signal is less influenced by electromagnetic interferenced and temperature.In addition, the control unit manages distribution of the braking load over the rear axle to replace the mechanical load proportioning valve used previously (EBD function: Electronic Brake Distribution").The control unit is equipped with an autodiagnostic function: when an error is detected in the ABS function, it turns on the associated warning light and simultaneously deactivates the system: under these conditions the vehicle is braked using only the conventional braking system.When the control unit detects an error in the EBD function, it turns on the low brake fluid and handbrake warning light together with the ABS failure warning light.Under these conditions, the rear brake distributor control is deactivated and the vehicle must be driven with great caution.The lines supplying the control unit and the various system components (sensors and actuators) are protected by dedicated by fuses located inside the engine bay control unit and the under-facia junction unit.