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 (CROSSTREK MODEL (HEV))>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DO (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 (HEV))>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

Courtesy of SUBARU OF AMERICA, INC.

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.
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 other than U0284 displayed? (Current malfunction)

Yes : Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DO (HEV))>DIAGNOSTIC TROUBLE CODE (DTC) .

No : Go to 3.
CHECK HARNESS BETWEEN ECM AND ACTIVE GRILLE SHUTTER CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the battery. Ref. to STARTING/CHARGING SYSTEMS (H4DO (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 & 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.
CHECK HARNESS BETWEEN ECM AND ACTIVE GRILLE SHUTTER CONNECTOR .
Measure the resistance of harness between ECM and active grille shutter connector.

Connector & 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.
CHECK ACTIVE GRILLE SHUTTER POWER SUPPLY .
1. Connect the battery. Ref. to STARTING/CHARGING SYSTEMS (H4DO (HEV))>BATTERY .
2. Measure the voltage between active grille shutter connector and chassis ground.
  Connector & terminal
  
  (B63) No. 2 (+) - Chassis ground (-):
Is the voltage 9 V or more?

Yes : Go to 6.

No : Repair the power supply circuit.
CHECK HARNESS BETWEEN ACTIVE GRILLE SHUTTER CONNECTOR AND CHASSIS GROUND .
Measure the resistance of harness between active grille shutter connector and chassis ground.

Connector & terminal

(B63) No. 4 - Chassis ground:

Is the resistance less than 10 Ω?

Yes : Replace the active grille shutter. Ref. to COOLING (H4DO (HEV))>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