System Outline

The ABS system controls the brake fluid pressure acting on the different disc brake cylinders for each of the four wheels when the brakes are applied suddenly, so that the wheels do not lock. This results in improved directional stability and steerability during sudden braking.

1. Input Signals 
   1. Speed sensor signal

      The speed of the wheels is detected and input to TERMINALS FL+, FR+, RL+ and RR+ of the skid control ECU with actuator.

   2. Stop light SW signal

      A signal is input to TERMINAL STP of the skid control ECU with actuator when the brake pedal is operated.

   3. Parking position signal

      A signal is input to TERMINAL P of the skid control ECU with actuator when the Shift lever is in the "P" position.

   4. Neutral position signal

      A signal is input to TERMINAL N of the skid control ECU with actuator when the Shift lever is in the "N" position.

2. ABS System Operation 

   During sudden braking, the skid control ECU with actuator receives signals from various sensors, and then adjusts the current which is being sent to the solenoid inside the actuator which lets the hydraulic pressure acting on the wheel cylinders escape to the reservoir. The pump inside the actuator is also activated at this time, and it returns the brake fluid from the reservoir to the master cylinder, thus preventing the vehicle wheels from locking.

   If the skid control ECU with actuator judges that the hydraulic pressure acting on any of the wheel cylinders is insufficient, the current being sent to the appropriate solenoid is adjusted and the hydraulic pressure is increased. The skid control ECU with actuator can also maintain the brake pressure at a fixed level, by the same method outlined above. Maintaining, reducing and increasing the pressure are repeated as needed to maintain the vehicle stability and to improve steerability during sudden braking.