Antilock Brake (ABS) System

Speed Sensor Circuit Description:

Nippondenso Type (ABS Only)

PURPOSE
The Wheel Speed Sensor detects wheel speed and sends the appropriate signals to the Electronic Control Unit (ECU). These signals are used to control the Anti-Lock Brake System (ABS) system.

OPERATION
A reluctor (wheel sensor rotor) with 48 serrations rotates with each wheel. When the wheels rotate, the teeth of the rotor interrupt a magnetic field emitted by a permanent magnet manufactured into the wheel speed sensor. The changing magnetic field induces an AC voltage in the sensor circuit. Since the frequency of this AC voltage changes in direct proportion to the speed of the wheel, the frequency is used by the ECU to detect the speed of each wheel.

FAIL SAFE FUNCTION
If trouble occurs in the Speed Sensor circuit, the ECU cuts off current to the ABS Solenoid Relay and prohibits ABS control.