Circuit Description

Speed sensor detects wheel speed and sends appropriate signals to ABS ECU. These signals are used to control ABS system. Front and rear sensor rotors each have 48 teeth. When rotor rotates, magnetic field emitted by permanent magnet in speed sensor generates an AC voltage. Since frequency of this AC voltage changes in direct proportion to speed of rotor, frequency is used by ABS ECU to detect speed of each wheel. If malfunction occurs in speed sensor circuit, ABS ECU cuts off current to ABS solenoid valve relay and prohibits ABS control.