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Home >> Subaru >> 2020 >> Crosstrek Base, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 6 (P-HEV Hybrid Powertrain Control System (Diagnostics) (1 Of 2)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0688-1F: ECM/Pcm Power Relay Sense Circuit Intermittent >> Notes

DTC P0688-1F: ECM/Pcm Power Relay Sense Circuit Intermittent: Notes

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

1. - 

Outline of diagnosis: 

During READY ON, Hybrid vehicle control ECU assembly was reset due to instantaneous power failure

(1 trip detection logic)

Trouble symptom: 

Hybrid system stopped

Wiring diagram: 

Hybrid system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>HYBRID ELECTRIC VEHICLE SYSTEM>WIRING DIAGRAM .

G13237901Courtesy of SUBARU OF AMERICA, INC.
CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to P-HEV HYBRID POWERTRAIN CONTROL (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .
G13617947Courtesy of SUBARU OF AMERICA, INC.
  1. CHECK Battery (12V) terminal  .

    Check if removal/installation of Battery (12V) terminal was performed immediately before.

    Was removal/installation performed?

    Yes  : Go to  2.

    No  : Go to  5.

  2. CHECK Hybrid Fail Lamp  .
    1. Switch from IG OFF to READY ON.
    2. Check that Hybrid Fail Lamp operates properly.

    Does Hybrid Fail Lamp illuminate?

    Yes  : Go to  3.

    No  : DTC P06881F may be displayed as a result of removal/installation of Battery (12V) terminal. In this case, DTC will no longer be displayed if switching from IG OFF to READY ON is performed. Finally, check DTC, clear the memory and finish the inspection.

  3. CHECK DTC  .
    1. Using the Subaru Select Monitor, perform the clear memory of [P-HEV Hybrid Powertrain Control]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
    2. Turn to IG OFF, and wait for 30 seconds or more.
    3. Turn to READY ON, and wait for 30 seconds or more.
    4. Turn to IG ON.
    5. Using the Subaru Select Monitor, read and record DTC and the freeze frame data of [P-HEV Hybrid Powertrain Control]. Ref. to P-HEV HYBRID POWERTRAIN CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to P-HEV HYBRID POWERTRAIN CONTROL (DIAGNOSTICS)>FREEZE FRAME DATA .

    Is DTC other than P06881F displayed?

    Yes  : Perform the diagnosis for DTC other than P06881F. Ref. to P-HEV HYBRID POWERTRAIN CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

    No  : Go to  4.

  4. CHECK Battery (12V) terminal  .
    1. Turn the ignition to OFF.
    2. Check the connecting condition of Battery (12V) terminal. Ref. to REPAIR CONTENTS>REPAIR CONTENTS>NOTE>BATTERY .

    Is there looseness or poor contact in the terminal?

    Yes  : Connect Battery (12V) terminal securely.

    No  : Go to  5.

  5. CHECK CONNECTION CONDITION OF CONNECTOR (Hybrid vehicle control ECU assembly CONNECTOR)  .

    Check the connecting condition of connector in Hybrid vehicle control ECU assembly and check the relevant terminals for contact pressure, deformation and intrusion of water or foreign matter. Ref. to HYBRID ELECTRIC VEHICLE>HYBRID POWERTRAIN CONTROL MODULE .

    Is there looseness at the connector mating, or any poor contact, deformation or intrusion of water or foreign matter at the relevant terminals?

    Yes  : Connect the connector securely. Or repair the poor contact of connector.

    No  : Go to  6.

  6. CHECK Wire harness AND CONNECTOR (Hybrid vehicle control ECU assembly - IGCT scene relay) (OPEN)  .
    1. Remove the IGCT scene relay from the Main fuse box (M/B). Ref. to HYBRID ELECTRIC VEHICLE>RELAY AND FUSE .
    2. Disconnect Hybrid vehicle control ECU assembly connectors (i369) and (i370).
    3. Using a tester, measure the resistance between Main fuse box (M/B) connector and Hybrid vehicle control ECU assembly connector.

      Connector & terminal 

      (i369) No. 4 - IGCT scene relay terminal No. 3:

      (i370) No. 3 - IGCT scene relay terminal No. 3:

    Is the resistance less than 1 Ω?

    Yes  : Go to  7.

    No  : Repair or replace Wire harness between Main fuse box (M/B) connector and Hybrid vehicle control ECU assembly connector.

  7. CHECK CONNECTION CONDITION OF CONNECTOR (Hybrid vehicle control ECU assembly - Main fuse box (M/B))  .

    Check Wire harness and connector between Hybrid vehicle control ECU assembly and Main fuse box (M/B) for poor mating and terminal contact pressure.

    Is there looseness at the connector connection, or any poor contact at the relevant terminals?

    Yes  : Connect the connector securely. Or repair the poor contact of connector.

    No  : Replace Hybrid vehicle control ECU assembly. Ref. to HYBRID ELECTRIC VEHICLE>HYBRID POWERTRAIN CONTROL MODULE .

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