Primary Speed Sensor: Inspection

Set the probe of oscilloscope to TCM harness connector.
Connector & terminal

(B54) No. 6 (+) - No. 1 (-):

Fig 1: TCM Harness Connector Terminal Identification
Courtesy of SUBARU OF AMERICA, INC.
Start and warm up the engine.
Lift up the vehicle.
CAUTION: Lift up the vehicle until the tire bottom is 0.3 m (0.98 ft) or more above the ground.
Shift the select lever to "D" range.
Check the waveform and output voltage of the primary speed sensor with engine idling.
NOTE: The waveform cycle changes as the speed changes.

Fig 2: Turbine Speed Sensor Waveform (Primary)
Courtesy of SUBARU OF AMERICA, INC.