Circuit Description
WARNING: This page is about a different car, the 2003 Toyota Prius, 2002 Toyota Prius, and 2001 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
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 relay and prohibits ABS control.