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

-
DTC detecting condition:

Immediately at fault recognition

Wiring diagram:

Engine Electrical system. Refer to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Refer to ENGINE (DIAGNOSTICS) (H4DO)>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. Refer to ENGINE (DIAGNOSTICS) (H4DO)>Basic Diagnostic Procedure>PROCEDURE .

CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Refer 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.
CHECK DTC .
Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Refer to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .

Is DTC other than U0284 displayed? (Current malfunction)

Yes : Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Refer to ENGINE (DIAGNOSTICS) (H4DO)>Diagnostic Trouble Code (DTC)>LIST .

No : Go to 3.
CHECK HARNESS BETWEEN ECM CONNECTOR AND ACTIVE GRILLE SHUTTER CONNECTOR (SHORT TO GROUND) .
1. Turn the ignition switch to OFF.
2. Disconnect the battery. Refer to REPAIR CONTENTS>NOTE>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 engine ground.
  Connector & terminal
  
  (B136) No. 3 - Engine 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.
CHECK HARNESS BETWEEN ECM CONNECTOR AND ACTIVE GRILLE SHUTTER CONNECTOR (OPEN) .
Measure the resistance of harness between ECM and active grille shutter connector.

Connector & terminal

(B62) No. 17 - (B136) 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.
CHECK ACTIVE GRILLE SHUTTER POWER SUPPLY .
1. Connect the battery. Refer to REPAIR CONTENTS>NOTE>BATTERY .
2. Measure the voltage between active grille shutter connector and engine ground.
  Connector & terminal
  
  (B136) No. 2 (+) - Engine ground (-):
  
  Is the voltage 9 V or more?
  
  Yes : Go to 6.
  
  No : Repair the following item.
  - Open circuit or short circuit to ground in harness between active grille shutter connector and M/B
  - Blown out of fuse
CHECK HARNESS BETWEEN ACTIVE GRILLE SHUTTER CONNECTOR AND GROUND (OPEN) .
Measure the resistance of harness between active grille shutter connector and engine ground.

Connector & terminal

(B136) No. 4 - Engine ground:

Is the resistance less than 10 Ω?

Yes : Replace the active grille shutter. Refer to COOLING(H4DO)>ACTIVE GRILLE SHUTTER .

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