SFI SYSTEM (w/ Secondary Air Injection System) Fuel Pump Control Circuit

DESCRIPTION

When the engine is cranked, a current flows from terminal ST2 of the ignition switch into the STA (starter) relay coil and a current also flows into terminal STA of the ECM (STA signal).

When the STA and NE signals are received by the ECM, Tr (power transistor) is switched on, allowing a current to flow into the circuit opening relay coil. The circuit opening relay switches on, power is supplied to the fuel pump and the fuel pump operates.

While the NE signal is being generated (engine running), the ECM keeps Tr ON, therefore keeping the circuit opening relay ON, so that the fuel pump continues to operate.

A01BFBUE01

WIRING DIAGRAM

A01BEREE02

INSPECTION PROCEDURE

PROCEDURE


  1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER


    1. Connect an intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position and turn the tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT / Active Test / Fuel Pump / Spd.

    4. Check whether the relay operating sounds can be heard while operating the relay using the tester.

      OK
      Relay operating sounds can be heard from relay.

    OK

    INSPECT FUEL PUMP ASSEMBLY Click here

    NG

  2. INSPECT ECM POWER SOURCE CIRCUIT


    NG

    REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT

    OK

  3. INSPECT INTEGRATION NO.1 RELAY (CIRCUIT OPENING RELAY)


    1. A01BH79E01

      Remove the integration relay from the engine room R/B No.1.

    2. Check the integration relay (CIRCUIT OPENING RELAY).

      Resistance
      Tester Connection Specified Conditions
      B4 - B8 10 kΩ or higher
      B4 - B8

      Below 1 Ω

      (When battery voltage applied to terminals B6 and B7)

    3. Reinstall the integration relay.


    NG

    REPLACE INTEGRATION NO.1 RELAY

    OK

  4. INSPECT ECM (FC VOLTAGE)


    1. A01BDNSE31

      Turn the ignition switch to the ON position.

    2. Measure the voltage between the terminals of the ECM connectors.

      Voltage
      Tester Connections Specified Conditions
      FC (B9-25) - E1 (D1-3) 9 to 14 V

    OK

    REPLACE ECM

    NG

  5. CHECK HARNESS AND CONNECTOR (ECM - INTEGRATION RELAY)


    1. A01BHB6E02

      Remove the integration relay from the engine room R/B No.1.

    2. Disconnect the B9 ECM connector.

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

      Resistance (Check for open)
      Tester Connection Specified Condition
      Integration relay (B2) - MREL (B9-8) Below 1 Ω
      Integration relay (B7) - FC (B9-25) Below 1 Ω
      Resistance (Check for short)
      Tester Connection Specified Condition

      Integration relay (B2) or MREL (B9-8)

      - Body ground

      		 10 kΩ or higher

      Integration relay (B7) or FC (B9-25)

      - Body ground

      		 10 kΩ or higher

    4. Reinstall the ECM connector.

    5. Reinstall the integration relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM

  6. INSPECT FUEL PUMP ASSEMBLY


    NG

    REPLACE FUEL PUMP ASSEMBLY

    OK

  7. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - FUEL PUMP, FUEL PUMP - BODY GROUND)


    1. A01BAIWE01

      Remove the integration relay from the engine room R/B No.1.

    2. Disconnect the fuel pump connector.

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

      Resistance (Check for open)
      Tester Connection Specified Condition
      Integration relay (B8) - Fuel pump (4) Below 1 Ω
      Fuel pump (5) - Body ground Below 1 Ω
      Resistance (Check for short)
      Tester Connection Specified Condition

      Integration relay (B8) or Fuel pump (4)

      - Body ground

      		 10 kΩ or higher

    4. Reinstall the integration relay.

    5. Reconnect the fuel pump connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    CHECK AND REPLACE INTEGRATION NO.1 RELAY (EFI RELAY AND CIRCUIT OPENING RELAY)