Faulty Left Front Speed Sensor
Left Front Speed Sensor harness is open or shorted
Left Front Speed Sensor circuit poor electrical connection
Left Front Speed Sensor rotor
Brake actuator (skid control ECU)
Anti-Lock Brake System (ABS) Warning Light ON
Engine Light ON (or Service Engine Soon Warning Light)
The speed sensor detects wheel speed and sends the appropriate signals to the ECU. These signals are used to control the ABS control system. The front and rear rotors have 48 serrations each.
When the rotors rotate, the magnetic field emitted by the permanent magnet in the speed sensor generates AC voltage. Since the frequency of this AC voltage changes in direct proportion to the speed of the rotor, the frequency is used by the ECU to detect the speed of each wheel.