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Home >> Subaru >> 2017 >> Impreza Base, 4D Sedan, Automatic CVT Trans >> Repair and Diagnosis >> Transmission >> Automatic Trans >> CVT Transaxle >> Primary Speed Sensor >> Inspection
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Primary Speed Sensor: Inspection

  1. Disconnect the ground cable from battery. Ref. to REPAIR CONTENTS>NOTE>SAFETY .
  2. Remove the clip from the air intake boot, and loosen the clamp.
    Fig 1: Locating Clip From Air Intake Boot
    G11252776Courtesy of SUBARU OF AMERICA, INC.
  3. Remove the air intake boot, and place it aside so that it does not interfere with the work.
    NOTE: Be careful not to pull out the PCV hose.
    Fig 2: Removing Air Intake Boot
    G11252777Courtesy of SUBARU OF AMERICA, INC.
  4. Remove the transmission radio ground terminal.
    Fig 3: Locating Transmission Radio Ground Terminal Bolt
    G11255509Courtesy of SUBARU OF AMERICA, INC.
  5. Disconnect the transmission harness connector.
    Fig 4: Disconnecting Transmission Harness Connector
    G11255510Courtesy of SUBARU OF AMERICA, INC.
  6. Remove the transmission case cover (small).
    Fig 5: Locating Transmission Case Cover Bolts
    G11255523Courtesy of SUBARU OF AMERICA, INC.
  7. Move the lock lever in the arrow direction while pressing the lock button, and disconnect the connector.
    Fig 6: Moving Lock Lever
    G11255641Courtesy of SUBARU OF AMERICA, INC.
  8. Set the ST between TCM and transmission harness. Ref. to TRANSMISSION (DIAGNOSTICS)>General Description>CAUTION .

    Preparation tool: 

    ST: CHECK BOARD (18460AA040)

  9. Connect the transmission radio ground terminal and transmission harness connector.

    Tightening torque: 

    32.3 N.m (3.3 kgf-m, 23.8 ft-lb)

  10. Install the air intake boot. Ref. to INTAKE (INDUCTION) (H4DO)>Air Intake Boot>INSTALLATION .
  11. Connect the battery ground terminal. Ref. to REPAIR CONTENTS>NOTE>SAFETY .
  12. Set the probe of oscilloscope to the check board connector.

    Connector & terminal 

    (B54) No. 14 (+) - No. 42 (-):

    Fig 7: Identifying Check Board Connector Terminals
    G11255642Courtesy of SUBARU OF AMERICA, INC.
  13. Start and warm up the engine.
  14. 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.
  15. Shift the select lever to the "D" range.
  16. Check the waveform and output voltage of the primary speed sensor with engine idling.
    NOTE: The waveform cycle changes as the speed changes.
Fig 8: Primary Speed Sensor Output Voltage Waveform
G09481458Courtesy of SUBARU OF AMERICA, INC.
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