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 ST1 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.

A0138E3E01

WIRING DIAGRAM

A0136G6E01

INSPECTION PROCEDURE

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (FUEL PUMP)


    1. Connect the intelligent tester to the DLC3.

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

    3. Enter the following menus: Powertrain / Engine and ECT / Active Test / Fuel Pump.

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

      OK
      Operating sounds can be heard from the relay.

    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    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 relay block.

    2. Remove the engine room relay block lower cover.

    3. Disconnect the 5 connectors from the engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1C-5 - 1D-1 When battery voltage absent 10 kΩ or higher
      1C-5 - 1D-1 When battery voltage applied to terminals 1C-9 and 1D-2 Below 1 Ω

    5. Reinstall the circuit opening relay.


    NG

    REPLACE ENGINE ROOM RELAY BLOCK

    OK

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


    1. A0138JPE05

      Remove the engine room relay block.

    2. Remove the engine room relay block lower cover.

    3. Disconnect the ECM connectors.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      1C-8 - B26-35 (MREL) Always Below 1 Ω
      1C-9 - B26-26 (FC) Always Below 1 Ω
      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      1C-8 - B26-35 (MREL) - Body ground Always 10 kΩ or higher
      1C-9 - B26-26 (FC) - Body ground Always 10 kΩ or higher

    5. Reinstall the engine room relay block.

    6. Reconnect the ECM connectors.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT FUEL PUMP


    1. Inspect the fuel pump Click here.


    NG

    REPAIR OR REPLACE FUEL PUMP

    OK

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


    1. A0136RVE02

      Remove the engine room relay block.

    2. Remove the engine room relay block lower cover.

    3. Disconnect the fuel pump connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      1D-1 - H2-4 (Fuel pump) Always Below 1 Ω
      H2-5 (Fuel pump) - Body ground Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      1D-1 or H2-4 (Fuel pump) - Body ground Always 10 kΩ or higher

    5. Reinstall the engine room relay block.

    6. Reconnect the fuel pump connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here