SFI SYSTEM ECM Power Source Circuit

DESCRIPTION

When the power switch is turned on (IG), the battery voltage is applied to terminal IGSW of the ECM. The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the EFI relay (EFI MAIN2) and supplying power to terminal +B and +B2 of the ECM.

If the power switch is turned off, the ECM holds the EFI relay (EFI MAIN2) ON for a maximum of 2 seconds to allow for the initial setting of the throttle valve.

When the power switch is turned on (IG), voltage from the ECM's MREL terminal is applied to the EFI relay (EFI MAIN2). This causes the contacts of the EFI relay (EFI MAIN2) to close, which supplies power to terminal +B and +B2 of the ECM.

WIRING DIAGRAM

A000ULLE02
*a EFI NO. 1
*b Main Body ECU
*c Battery

PROCEDURE


  1. INSPECT ECM (+B, +B2 VOLTAGE)


    1. A000YXWE01
      *1 Component with harness connected: (ECM)

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

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      A13-2 (+B) - E3-1 (E1) Power switch on (IG) 11 to 14 V
      A13-1 (+B2) - E3-1 (E1) Power switch on (IG) 11 to 14 V

    OK

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

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


    1. A000UO6E01
      *1 Rear view of wire harness connector: (to ECM)

      Disconnect the E3 ECM connector.

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

      Standard resistance (Check for open)
      Tester Connection Condition Specified Condition
      E3-1 (E1) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. INSPECT ECM (IGSW VOLTAGE)


    1. A000VXJE01
      *1 Component with harness connected: (ECM)

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

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      A14-8 (IGSW) - E3-1 (E1) Power switch on (IG) 11 to 14 V

    OK

    INSPECT ECM (MREL VOLTAGE) Click here

    NG

  4. CHECK FUSE (ECU-IG)


    1. A000WLFE02
      *1 Engine Room No. 2 Junction Block

      Remove the ECU-IG fuse from the engine room No. 2 junction block.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      ECU-IG fuse Always Below 1 Ω

    NG

    CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE

    OK

  5. INSPECT IGNITION RELAY NO. 2 (IG2)


    1. Inspect the ignition relay No. 2 (IG2) Click here.


    OK

    GO TO ENTRY AND START SYSTEM Click here

    NG

    REPLACE IGNITION RELAY NO. 2 (IG2)

  6. INSPECT ECM (MREL VOLTAGE)


    1. A000VUEE01
      *1 Component with harness connected: (ECM)

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

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      A14-3 (MREL) - E3-1 (E1) Power switch on (IG) 11 to 14 V

    NG

    REPLACE ECM Click here

    OK

  7. CHECK FUSE (EFI MAIN2)


    1. A000UNDE04
      *1 Engine Room No. 2 Relay Block

      Remove the EFI MAIN2 fuse from the engine room No. 2 relay block.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      EFI MAIN2 fuse Always Below 1 Ω

    NG

    CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE

    OK

  8. INSPECT EFI RELAY (EFI MAIN2)


    1. Inspect the EFI relay (EFI MAIN2) Click here.


    NG

    REPLACE EFI RELAY (EFI MAIN2)

    OK

  9. CHECK HARNESS AND CONNECTOR (EFI RELAY (EFI MAIN2) - ECM, BODY GROUND)


    1. Check the harness and the connectors between the integration relay and ECM.

      A000Y1IE01
      *1 Front view of wire harness connector: (to Engine Room Relay Block)
      *2 Rear view of wire harness connector: (to ECM)

      1. Remove the EFI relay (EFI MAIN2) from the engine room No. 2 relay block.

      2. Disconnect the A14 ECM connector.

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

        Standard resistance (Check for open)
        Tester Connection Condition Specified Condition
        EFI relay (EFI MAIN2) (1) - A14-3 (MREL) Always Below 1 Ω
        EFI relay (EFI MAIN2) (3) - A13-1 (+B2) Always Below 1 Ω
        EFI relay (EFI MAIN2) (3) - A13-2 (+B) Always Below 1 Ω
        Standard resistance (Check for short)
        Tester Connection Condition Specified Condition
        A14-3 (MREL) - Body ground Always 10 kΩ or higher
        A13-1 (+B2) - Body ground Always 10 kΩ or higher
        A13-2 (+B) - Body ground Always 10 kΩ or higher

    2. Check the harness and the connectors between the EFI relay (EFI MAIN2) and body ground.


      1. Remove the EFI relay (EFI MAIN2) from the engine room No. 2 relay block.

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

        Standard resistance (Check for open)
        Tester Connection Condition Specified condition
        EFI relay (EFI MAIN2) (2) - Body ground Always Below 1 Ω

    OK

    CHECK AND REPAIR HARNESS OR CONNECTOR (TERMINAL +B OF ECM - BATTERY POSITIVE TERMINAL)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR