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Home >> Subaru >> 2021 >> Crosstrek Hybrid >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 23 (Engine Control System (2.0L (Except For HEV)) (Diagnostics) (4 Of 4)) >> Diagnostic Procedure With Diagnostic Trouble Code (DTC) >> DTC U0284: Lost Communication With Active Grille Shutter Module "A" >> Notes

DTC U0284: Lost Communication With Active Grille Shutter Module "A": Notes

WARNING: This page is about a different variant/trim than selected.

1. - 

DTC detecting condition: 

Immediately at fault recognition

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM (IMPREZA MODEL)>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

G13614688Courtesy of SUBARU OF AMERICA, INC.
CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .
NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .
  1. CHECK DTC  .

    Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC U0284 displayed? (Current malfunction)

    Yes:  Go to  2.

    No:  The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

    NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
  2. CHECK DTC  .

    Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC for engine displayed?

    Yes:  Go to  3.

    No:  Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .

  3. CHECK HARNESS BETWEEN ECM AND ACTIVE GRILLE SHUTTER (SHORT TO GROUND)  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the battery. Ref. to STARTING/CHARGING SYSTEMS (H4DO (EXCEPT FOR HEV))>BATTERY .
    3. Disconnect the connector from ECM.
    4. Disconnect the connector from the active grille shutter.
    5. Measure the resistance between active grille shutter connector and chassis ground.

      Connector and terminal 

      (B63) No. 3 - Chassis ground:

      Is the resistance 1 MΩ or more?

      Yes:  Go to  4.

      No:  Repair the short circuit to ground in harness between ECM and active grille shutter connector.

  4. CHECK HARNESS BETWEEN ECM AND ACTIVE GRILLE SHUTTER (OPEN)  .

    Measure the resistance of harness between ECM and active grille shutter connector.

    Connector and terminal 

    (B134) No. 17 - (B63) No. 3:

    Is the resistance less than 10 Ω?

    Yes:  Go to  5.

    No:  Repair the open circuit in harness between ECM and active grille shutter connector.

  5. CHECK ACTIVE GRILLE SHUTTER POWER SUPPLY  .
    1. Connect the battery. Ref. to STARTING/CHARGING SYSTEMS (H4DO (EXCEPT FOR HEV))>BATTERY .
    2. Measure the voltage between active grille shutter connector and chassis ground.

      Connector and terminal 

      (B63) No. 2 (+) - Chassis ground (-):

      Is the voltage 9 V or more?

      Yes:  Go to  6.

      No:  Repair the power supply circuit.

  6. CHECK HARNESS BETWEEN ACTIVE GRILLE SHUTTER AND CHASSIS GROUND  .

    Measure the resistance of harness between active grille shutter connector and chassis ground.

    Connector and terminal 

    (B63) No. 4 - Chassis ground:

    Is the resistance less than 10 Ω?

    Yes:  Replace the active grille shutter.

    No:  Repair the harness and connector.

    NOTE: In this case, repair the following item:
    • Open circuit of harness between active grille shutter connector and chassis ground
    • Poor contact of J/C
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