Type of Operation

Type of operation
Under normal conditions, the standard brake system performs until locking of a wheel is detected by the ABS control unit.
During standard braking, inlet valves are normally opened and outlet valves are normally closed.
When the ABS control unit detects a wheel lock, the hydraulic unit controls each valve to maintain, increase or decrease pressure.





The ABS control unit detects the speed and the deceleration rate of each wheel with wheel speed sensors. When braking the wheel speed is decreased and difference between wheel speed and vehicle speed is generated. If deceleration rate of some wheels exceeds expected value (Point A), ABS control unit determines wheel lock has occurred and opens the corresponding outlet solenoid valves to reduce brake fluid pressure. If locking pressure on the wheels is exceeded (Point B) and wheel speed reaches point C, then the ABS control unit closes outlet valve of the corresponding wheels to increase fluid pressure.





For vehicles with ABS. the following symptoms can occur but indicate normal operation of the ABS.