SFI SYSTEM ECM Power Source Circuit

DESCRIPTION

When the engine switch is turned on (IG), 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 engine 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 engine 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

A01GMAKE03

INSPECTION PROCEDURE

PROCEDURE


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


    1. A01GJ89E28

      Turn the engine switch on (IG).

    2. 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) Engine switch on (IG) 11 to 14 V
      A13-1 (+B2) - E3-1 (E1) Engine 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. A01GI2EE05

      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. A01GJ89E29

      Turn the engine switch on (IG).

    2. 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) Engine switch on (IG) 11 to 14 V

    OK

    INSPECT ECM (MREL VOLTAGE) Click here

    NG

  4. CHECK FUSE (ECU-IG)


    1. A01GKBAE01

      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 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. A01GMJIE01

      Remove the IG2 relay 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
      3 - 5 When no battery voltage applied to terminals 1 and 2 10 kΩ or higher
      3 - 5 When battery voltage applied to terminals 1 and 2 Below 1 Ω

    NG

    REPLACE IGNITION RELAY NO.2 (IG2)

    OK

    GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START Click here

  6. INSPECT ECM (MREL VOLTAGE)


    1. A01GJ89E30

      Turn the engine switch on (IG).

    2. 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) Engine switch on (IG) 11 to 14 V

    NG

    REPLACE ECM Click here

    OK

  7. CHECK FUSE (EFI MAIN2)


    1. A01GLKPE01

      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 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. A01GMXKE02

      Remove the EFI MAIN2 relay 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
      3 - 5 When no battery voltage applied to terminals 1 and 2 10 kΩ or higher
      When battery voltage applied to terminals 1 and 2 Below 1 Ω

    NG

    REPLACE EFI RELAY (EFI MAIN2)

    OK

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

    A01GIURE04

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


      1. Remove the EFI MAIN2 relay 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 MAIN2 relay (1) - A14-3 (MREL) Always Below 1 Ω
        Standard resistance (Check for short)
        Tester Connection Condition Specified Condition
        EFI MAIN2 relay (1) or A14-3 (MREL) - Body ground Always 10 kΩ or higher

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


      1. Remove the EFI relay 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 MAIN2 relay (2) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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