The ECU(computer-chip) has two wire coming out of it one attaches to the RPM (that is taken from inside engine bay) and the other is attached to meter km/hr
This lets the ECU know what speed and rpm the car is going on, from the the ECU hardens the steering for GREATER MANEUVERABILITY...
This is built-in every power steering, as this help car movement in high speed... you dont want a soft feather like steering at high speeds 
