SFI SYSTEM ECM Power Source Circuit

DESCRIPTION

When the ignition switch is turned to ON, battery voltage is applied to the IGSW terminal of the ECM. The output signal from the MREL terminal of the ECM causes current to flow to the coil of the EFI-MAIN relay, closing the contact of the EFI-MAIN relay and supplying power to terminals +B and +B2 of the ECM.

WIRING DIAGRAM

A01TBFZE03

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)


    1. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      B208-53 (E1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK TERMINAL VOLTAGE (IGSW VOLTAGE)

    A01TBALC04
    *a

    Front view of wire harness connector

    (to ECM)

    1. Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A173-6 (IGSW) - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT RELAY (IG2 RELAY) Click here

    OK

  3. INSPECT RELAY (EFI-MAIN RELAY)


    1. Inspect the EFI-MAIN relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE RELAY (EFI-MAIN RELAY)

    OK

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


    1. Remove the EFI-MAIN relay from the engine room relay block and junction block assembly.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (EFI-MAIN relay) - A173-46 (MREL) Always Below 1 Ω
      3 (EFI-MAIN relay) - A173-2 (+B) Always Below 1 Ω
      3 (EFI-MAIN relay) - A173-3 (+B2) Always Below 1 Ω
      1 (EFI-MAIN relay) or A173-46 (MREL) - Body ground and other terminals Always 10 kΩ or higher
      3 (EFI-MAIN relay) or A173-2 (+B) - Body ground and other terminals Always 10 kΩ or higher
      3 (EFI-MAIN relay) or A173-3 (+B2) - Body ground and other terminals Always 10 kΩ or higher

      Tech Tips

      If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (EFI-MAIN RELAY VOLTAGE)


    1. Remove the EFI-MAIN relay from the engine room relay block and junction block assembly.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      5 (EFI-MAIN relay) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - EFI-MAIN RELAY)

    OK

  6. CHECK HARNESS AND CONNECTOR (EFI-MAIN RELAY - BODY GROUND)


    1. Remove the EFI-MAIN relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2 (EFI-MAIN relay) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  7. INSPECT RELAY (IG2 RELAY)


    1. Inspect the IG2 relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE RELAY (IG2 RELAY)

    OK

  8. CHECK HARNESS AND CONNECTOR (IG2 RELAY - ECM)


    1. Remove the IG2 relay from the engine room relay block and junction block assembly.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      5 (IG2 relay) - A173-6 (IGSW) Always Below 1 Ω
      5 (IG2 relay) or A173-6 (IGSW) - Body ground and other terminals Always 10 kΩ or higher

      Tech Tips

      If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. CHECK HARNESS AND CONNECTOR (IG2 RELAY VOLTAGE)


    1. Remove the IG2 relay from the engine room relay block and junction block assembly.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      3 (IG2 relay) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IG2 RELAY)

    OK

  10. CHECK HARNESS AND CONNECTOR (IG2 RELAY - BODY GROUND)


    1. Remove the IG2 relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2 (IG2 relay) - Body ground Always Below 1 Ω
      Result
      Result Proceed to
      OK (w/ Entry and Start System) A
      OK (w/o Entry and Start System) B
      NG C

    B

    INSPECT IGNITION OR STARTER SWITCH ASSEMBLY Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  11. CHECK HARNESS AND CONNECTOR (SMART KEY ECU ASSEMBLY - IG2 RELAY)


    1. Remove the IG2 relay from the engine room relay block and junction block assembly.

    2. Disconnect the smart key ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E33-9 (IG2D) - 1 (IG2 relay) Always Below 1 Ω
      E33-9 (IG2D) or 1 (IG2 relay) - Body ground and other terminals Always 10 kΩ or higher

      Tech Tips

      If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.

      Result
      Proceed to
      OK
      NG

    OK

    CHECK ENTRY AND START SYSTEM (FOR START FUNCTION) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  12. INSPECT IGNITION OR STARTER SWITCH ASSEMBLY


    1. Inspect the ignition or starter switch assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE IGNITION OR STARTER SWITCH ASSEMBLY Click here

    OK

  13. CHECK HARNESS AND CONNECTOR (IGNITION OR STARTER SWITCH ASSEMBLY - IG2 RELAY)


    1. Disconnect the ignition or starter switch assembly connector.

    2. Remove the IG2 relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E4-3 (IG2) - 1 (IG2 relay) Always Below 1 Ω
      E4-3 (IG2) or 1 (IG2 relay) - Body ground and other terminals Always 10 kΩ or higher

      Tech Tips

      If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.

      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IGNITION OR STARTER SWITCH ASSEMBLY)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR