SFI SYSTEM (w/o Electronic Throttle Control System) Fuel Pump Control Circuit

DESCRIPTION

In the diagram below, when the engine is cranked, a current flows from terminal ST2 of the ignition switch to the starter relay coil and also a current flows to terminal STA of the ECM (STA signal). When the STA signal and NE signal are transmitted to the ECM, the power transistor (Tr) is turned ON, a current flows to the coil of the circuit opening relay to switch the relay on, the power is supplied to the fuel pump and the fuel pump operates.

While the NE signal is generated (when engine running), the ECM keeps Tr ON (circuit opening relay ON) and the fuel pump also keeps operating.

A0138VWE01

WIRING DIAGRAM

A0136J3E01

INSPECTION PROCEDURE

PROCEDURE


  1. PERFORM ACTIVE TEST BY INTELLIGENT TESTER (Active the Fuel Pump Speed Control)


    1. Connect the intelligent tester to the DLC3.

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

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

    4. Check the operation of the relay while operating it using the intelligent tester.

      Standard
      Operating sounds can be heard from the relay.

    OK

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE

    NG

  2. CHECK ECM POWER SOURCE CIRCUIT


    NG

    REPAIR OR REPLACE POWER SOURCE CIRCUIT

    OK

  3. INSPECT ENGINE ROOM RELAY BLOCK (CIRCUIT OPENING RELAY)


    1. A0136ULE04

      Remove the engine room R/B.

    2. Remove the engine room R/B lower cover.

    3. Disconnect the 5 connectors from the engine room R/B.

    4. Measure the resistance.

      Standard resistance
      Tester Connection Specified Condition
      1C-5 - 1D-1 10 kΩ or higher
      1C-5 - 1D-1

      Below 1 Ω

      (when battery voltage is applied to terminals 1C-9 and 1D-2)

    5. Reinstall the circuit opening relay.


    NG

    REPLACE ENGINE ROOM RELAY BLOCK

    OK

  4. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK - ECM)


    1. A0137AEE01

      Remove the engine room R/B.

    2. Remove the engine room R/B lower cover.

    3. Disconnect the B25 and B26 ECM connectors.

    4. Measure the resistance.

      Standard resistance (Check for open)
      Tester Connection Specified Condition
      Engine room R/B (1C-8) - MREL (B25-66) Below 1 Ω
      Engine room R/B (1C-9) - FC (B26-28) Below 1 Ω
      Standard resistance (Check for open)
      Tester Connection Specified Condition
      Engine room R/B (1C-8) - MREL (B25-66) - Body ground 10 kΩ or higher
      Engine room R/B (1C-9) - FC (B26-28) - Body ground 10 kΩ or higher

    5. Reinstall the engine room R/B.

    6. Reconnect the ECM connectors.


    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  5. INSPECT FUEL PUMP


    NG

    REPAIR OR REPLACE FUEL PUMP

    OK

  6. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK - FUEL PUMP, FUEL - BODY GROUND)


    1. A0136RVE01

      Remove the engine room R/B.

    2. Remove the engine room R/B lower cover.

    3. Disconnect the H2 fuel pump connector.

    4. Measure the resistance.

      Standard resistance (Check for open)
      Tester Connection Specified Condition
      Engine room R/B (1D-1) - Fuel pump (H2-4) Below 1 Ω
      Fuel pump (H2-5) - Body ground Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Specified Condition
      Engine room R/B (1D-1) or Fuel pump (H2-4) - Body ground 10 kΩ or higher

    5. Reinstall the engine room R/B.

    6. Reconnect the fuel pump connector.


    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    REPAIR OR REPLACE FUEL PUMP