The Anti-Lock Braking System has been applied more and more widely and almost in every car now. And Hall-Effect or Magnetic Inductive ABS Sensor which measures the speed of a wheel, keep sending the speed signal to ABS computer so that the ABS computer could analyst the instant speed changing. The ABS sensor is installed on the back side of the brake rotor. The Sine-wave or Square-Wave current is generated by the sensor as the wheel rotates. The frequency and voltage increase as the rotating speed increases requirement.