Primary Speed Sensor: Inspection

Remove the bulkhead harness connector from TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>Transmission Control Module (TCM)>REMOVAL .
Set the ST between the TCM and bulkhead harness.
ST 18460AA040 CHECK BOARD
Set the probe of oscilloscope to the check board connector.
Terminals:

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

Fig 1: Identifying Primary Speed Sensor Positive And Negative Probes
Courtesy of SUBARU OF AMERICA, INC.
Start and warm up the engine.
Check the waveform of primary speed sensor with engine idling.
NOTE: The waveform cycle changes as the speed changes.

Fig 2: Identifying Primary Speed Sensor Waveform With Engine Idling

Courtesy of SUBARU OF AMERICA, INC.