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Home >> Subaru >> 2018 >> Crosstrek Base, Automatic CVT Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (3 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0851: Park/Neutral Switch Input Circuit Low >> CVT Model
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CVT Model

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM (CROSSTREK MODEL)>Engine Electrical System>WIRING DIAGRAM .

G12400114Courtesy of SUBARU OF AMERICA, INC.
  1. CHECK SELECT CABLE  .

    Check the select cable.

    Is there any fault in select cable?

    Yes:  Repair or adjust the select cable. Ref. to CONTROL SYSTEMS>SELECT CABLE .

    No:  Go to  2.

  2. CHECK INPUT SIGNAL OF ECM  .
    1. Turn the ignition switch to ON.
    2. Place the select lever in other than "P" range and "N" range.
    3. Measure the voltage between ECM connector and chassis ground.

      Connector & terminal 

      (B134) No. 39 (+) - Chassis ground (-):

      Is the voltage 10 V or more?

      Yes:  Repair the poor contact of ECM connector.

      No:  Go to  3.

  3. CHECK HARNESS BETWEEN ECM AND TRANSMISSION HARNESS CONNECTOR (SHORT TO GROUND)  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Disconnect the connector from inhibitor switch.
    4. Measure the resistance between ECM connector and chassis ground.

      Connector & terminal 

      (B134) No. 39 - Chassis ground:

      Is the resistance 1 MΩ or more?

      Yes:  Replace the inhibitor switch.

      No:  Repair the harness and connector.

      NOTE: In this case, repair the following item:
      • Short circuit to ground in harness between ECM connector and inhibitor switch connector
      • Poor contact of coupling connector