SFI SYSTEM (w/o Secondary Air Injection System) ECM Back-up Power Source Circuit

DESCRIPTION

The battery supplies electricity to the ECM even when the ignition switch is OFF. This power allows the ECM to store data such as DTC history, freeze frame data and fuel trim values. If the battery voltage falls below a minimum level, these memories are cleared.

WIRING DIAGRAM

A01BCZEE01

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK EFI FUSE


    1. A01BFWGE01

      Remove the EFI fuse from the engine room R/B No.1.

    2. Measure the resistance.

      Resistance
      Below 1 Ω

    3. Reinstall the EFI fuse.


    NG

    REPLACE EFI FUSE

    OK

  2. INSPECT ECM (BATT VOLTAGE)


    1. A01BBIVE07

      Measure the voltage between the terminals of the ECM connectors.

      Voltage
      Tester Connections Specified Conditions
      BATT (B9-3) - E1 (D1-3) 9 to 14 V

    NG

    CHECK HARNESS AND CONNECTOR (ECM - EFI FUSE, EFI FUSE - BATTERY) Click here

    OK

    REPLACE ECM

  3. CHECK HARNESS AND CONNECTOR (ECM - EFI FUSE, EFI FUSE - BATTERY)


    1. A01BI09E01

      Check the harness and the connector between the EFI fuse and ECM.


      1. Remove the EFI fuse from the engine room R/B No.1.

      2. Disconnect the B9 ECM connector.

      3. Measure the resistance.

        Resistance (Check for open)
        Tester Connections Specified Conditions
        EFI fuse (2) - BATT (B9-3) Below 1 Ω
        Resistance (Check for short)
        Tester Connections Specified Conditions
        EFI fuse (2) or BATT (B9-3) - Body ground 10 kΩ or higher

      4. Reconnect the ECM connector.

      5. Reinstall the EFI fuse.

    2. Check the harness and the connector between the EFI fuse and battery.


      1. Remove the EFI fuse from the engine room R/B.

      2. Disconnect the positive battery terminal.

      3. Measure the resistance.

        Resistance (Check for open)
        Tester Connections Specified Conditions
        Battery positive cable - EFI fuse (1) Below 1 Ω
        Resistance (Check for short)
        Tester Connections Specified Conditions

        Battery positive cable or EFI fuse (1)

        - Body ground

        		 10 kΩ or higher

      4. Reconnect the positive battery cable.

      5. Reinstall the EFI fuse.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT BATTERY


    1. Check that the battery is not depleted.


    NG

    REPLACE BATTERY

    OK

    CHECK AND REPLACE ENGINE ROOM RELAY BLOCK