Front Wheel Speed Sensor: Inspection

Remove the instrument panel lower cover. Refer to INSTRUMENT PANEL LOWER COVER EI-63, REMOVAL, Instrument Panel Lower Cover.
Set the probe of oscilloscope to TCM harness connector.
Connector & terminal

(B54) No. 20 (+) - No. 1 (-):

Fig 1: Identifying Instrument Panel Lower Cover
Courtesy of SUBARU OF AMERICA, INC.
Lift up the vehicle and raise the vehicle speed up to 20 km/h (12 MPH).
Check the waveform of front wheel speed sensor when vehicle speed is at 20 km/h (12 MPH).

Fig 2: Identifying Curve Between Front Wheel Speed Sensor And Vehicle Speed
Courtesy of SUBARU OF AMERICA, INC.