Primary Speed Sensor: Inspection

Set the ST between the TCM and bulkhead harness.
ST 18460AA040 CHECK BOARD
Set the probe of oscilloscope to the check board connector.
Connector & terminal

No. 14 (+) - No. 42 (-):

Fig 1: Primary Speed Sensor Connector Terminal
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 of primary speed sensor with engine idling running.
NOTE: The waveform cycle changes as the speed changes.

Fig 2: Primary Speed Sensor Output Voltage Waveform Cycle
Courtesy of SUBARU OF AMERICA, INC.