SFI SYSTEM, Diagnostic DTC:P0685

DTC Code DTC Name
P0685 ECM/PCM Power Relay Control Circuit / Open

DESCRIPTION

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0685 ECM/PCM Power Relay Control Circuit / Open

    Enable Criteria

  • Ignition supply voltage 6 V or more


    Malfunction Criteria

  • Absolute (Main relay voltage - ignition supply voltage) 1.0 V or more


    Diagnostic Mask

  • The MIL will be illuminated if a fault is present for two consecutive trips


    Monitor

  • Continuous


    Potential failure modes

  • EFI MAIN relay

  • Relay open circuit

  • Relay open circuit

  • EFI MAIN relay

 Comes on DTC stored

MONITOR DESCRIPTION

The ECU power is controlled by the main power relay. The voltage at ECM pins RM2/RM3/RM4 is compared to engine switch input RB1 to determine if the power relay is open circuit.

WIRING DIAGRAM

B0045YXE01
*a EFI MAIN
*b MAIN
*c Battery

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. INSPECT EFI MAIN RELAY


    1. Inspect the EFI MAIN relay.

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE EFI MAIN RELAY

    OK

  2. CHECK HARNESS AND CONNECTOR (EFI MAIN RELAY - ECM)


    1. Disconnect the A116 ECM connector.

    2. Remove the EFI MAIN relay from the No. 2 engine room relay block assembly.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A116-36 (+B) - 3 (EFI MAIN relay holder) Always Below 1 Ω
      A116-24 (+B2) - 3 (EFI MAIN relay holder) Always Below 1 Ω
      A116-12 (+B3) - 3 (EFI MAIN relay holder) Always Below 1 Ω
      A116-41 (MREL) - 1 (EFI MAIN relay holder) Always Below 1 Ω
      A116-35 (E1) - Body ground Always Below 1 Ω
      A116-36 (+B) - 3 (EFI MAIN relay holder) - Body ground other terminals Always 10 kΩ or higher
      A116-24 (+B2) - 3 (EFI MAIN relay holder) - Body ground other terminals Always 10 kΩ or higher
      A116-12 (+B3) - 3 (EFI MAIN relay holder) - Body ground other terminals Always 10 kΩ or higher
      A116-41 (MREL) - 1 (EFI MAIN relay holder) - Body ground other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  3. CHECK WHETHER DTC OUTPUT RECURS


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.

    5. Enter the following menus: Powertrain / Engine / Trouble Codes.

    6. Read DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0685 is output B

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE ECM Click here