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Home >> Subaru >> 2015 >> WRX Limited, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Controls (Diagnostics) (H4DOTC) (STI)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0685 ECM/Pcm Power Relay Control Circuit/Open >> Wiring Diagram

DTC P0685 ECM/Pcm Power Relay Control Circuit/Open: Wiring Diagram

WARNING: This page is about a different variant/trim than selected.
Fig 1: ECM/PCM Power Relay Control Circuit/Open - Wiring Diagram
G10265800Courtesy of SUBARU OF AMERICA, INC.
DIAGNOSTIC PROCEDURE

Step Check Yes No
1 CHECK ECM CONNECTOR. 
Check the connecting condition of ECM connector.
Is the ECM connector correctly connected? Go to step . Connect the ECM connector correctly.
2 CHECK HARNESS BETWEEN ECM AND MAIN RELAY CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Remove the main relay.
  3. Disconnect the connector from ECM.
  4. Measure the resistance between ECM connector and chassis ground.

    Connector & terminal 

    (B135) No. 13 - Chassis ground: 

Is the resistance 1 MΩ or more? Go to step . Repair the short circuit to ground in harness between ECM connector and main relay connector.
3 CHECK HARNESS BETWEEN ECM AND MAIN RELAY CONNECTOR. 
  1. Install the main relay.
  2. Turn the ignition switch to ON.
  3. Measure the voltage between ECM connector and chassis ground.

    Connector & terminal 

    (B136) No. 1 (+) - Chassis ground (-): 

    (B137) No. 7 (+) - Chassis ground (-): 

Is the voltage 10 V or more? Repair the harness and connector.
NOTE: In this case, repair the following item:

  • Short circuit to power supply in harness between ECM connector and main relay connector
  • Defective main relay
Repair the poor contact of ECM connector.