Primary Speed Sensor: Inspection

Set the ST between the TCM and bulkhead harness. Ref. to ENGINE (DIAGNOSTICS) (H4DO) > General Description > CAUTION .
ST 18460AA040 CHECK BOARD
Set the probe of oscilloscope to TCM harness connector.
Terminals

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

Fig 1: Identifying Primary Speed Sensor Connector Terminals
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: Primary Speed Sensor Output Voltage Waveform (With Engine Idling)

Courtesy of SUBARU OF AMERICA, INC.