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Home >> Lexus >> 2008 >> LX 570 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - System Descriptions And Testing, On-Vehicle Inspection, Removal And Installation >> Fuel Pump Control Circuit >> Inspection Procedure
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Inspection Procedure

This troubleshooting procedure is based on the premise that the engine is started. If the engine is not started, proceed to the Problem Symptoms Table (See PROBLEM SYMPTOMS TABLE ).

  1. PERFORM ACTIVE TEST USING TECHSTREAM (FUEL PUMP) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG) and turn the Techstream on.
    3. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Fuel Pump / Speed.
    4. Check whether operating sounds can be heard while operating the fuel pump using the Techstream.

      OK: Operating sounds can be heard from fuel pump. 

    NG:  Go to step  5

    OK: Go to Next Step 

  2. CHECK HARNESS AND CONNECTOR (FUEL PUMP ECU - ECM, BODY GROUND) 
    1. Disconnect the N2 fuel pump ECU connector.
    2. Disconnect the A38 ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    N2-5 (FPC) - A38-52 (FPC) Always Below 1 Ω
    N2-4 (DI) - A38-18 (DI) Always Below 1 Ω
    N2-6 (E) - Body ground Always Below 1 Ω
    N2-5 (FPC) or A38-52 (FPC) - Body ground Always 10 kΩ or higher
    N2-4 (DI) or A38-18 (DI) - Body ground Always 10 kΩ or higher
    M2-1 (FP-) - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 1: Identifying Terminals Of N2 Fuel Pump ECU Connector
    G05628166Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  3. REPLACE FUEL PUMP ECU 
    1. Replace the fuel pump ECU (See REMOVAL ).
  4. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED 
    1. Check the fuel pump operation.

      OK: Malfunction has been repaired successfully. 

    NG: REPLACE ECM  (See ECM )

    OK: END 

  5. INSPECT CIRCUIT OPENING RELAY (C/OPN) 
    1. Remove the circuit opening relay (C/OPN) from the engine room relay block.
    2. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    3 - 5 No battery voltage applied to terminals 1 and 2 10 kΩ or higher
    3 - 5 Battery voltage applied to terminals 1 and 2 Below 1 Ω

    NG: REPLACE CIRCUIT OPENING RELAY (C/ OPN) 

    Fig 2: Inspecting Circuit Opening Relay (C/OPN)
    G04942976Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  6. INSPECT CIRCUIT OPENING RELAY (POWER SOURCE VOLTAGE) 
    1. Remove the circuit opening relay (C/OPN) from the engine room relay block.
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

    Standard Voltage 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Switch Condition Specified Condition
    C/OPN relay (2) - Body ground Engine switch on (IG) 11 to 14 V
    C/OPN relay (5) - Body ground Engine switch on (IG) 11 to 14 V

    NG:  Go to step  13

    Fig 3: Inspecting Circuit Opening Relay
    G05149753Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  7. CHECK HARNESS AND CONNECTOR (CIRCUIT OPENING RELAY - ECU, FUEL PUMP ECU) 
    1. Remove the circuit opening relay (C/OPN) from the engine room relay block.
    2. Disconnect the A38 ECM connector.
    3. Disconnect the N2 fuel pump ECU connector.
    4. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    C/OPN relay (1) - A38-48 (FC) Always Below 1 Ω
    C/OPN relay (3) - N2-3 (+B) Always Below 1 Ω
    C/OPN relay (1) or A38-48 (FC) - Body ground Always 10 kΩ or higher
    C/OPN relay (3) or N2-3 (+B) - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 4: Identifying Terminals Of N2 Fuel Pump ECU Connector
    G05628169Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  8. CHECK HARNESS AND CONNECTOR (FUEL PUMP - FUEL PUMP ECU) 
    1. Disconnect the N1 fuel pump connector.
    2. Disconnect the N2 fuel pump ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    N1-4(B2) - N2-2(FP) Always Below 1 Ω
    N1-5(E2) - N2-1 (FP-) Always Below 1 Ω
    N1-4(B2) or N2-2(FP) - Body ground Always 10 kΩ or higher
    N1-5(E2) or N2-1 (FP-) - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 5: Identifying Terminals Of N2 Fuel Pump ECU And N1 Fuel Pump Connector
    G05628170Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  9. INSPECT FUEL PUMP 
    1. Inspect the fuel pump (See INSPECTION ).

    NG: REPLACE FUEL PUMP  (See REMOVAL )

    OK: Go to Next Step 

  10. CHECK HARNESS AND CONNECTOR (FUEL PUMP ECU - ECM, BODY GROUND) 
    1. Disconnect the N2 fuel pump ECU connector.
    2. Disconnect the A38 ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    N2-5 (FPC) - A38-52 (FPC) Always Below 1 Ω
    N2-4(DI) - A38-18(DI) Always Below 1 Ω
    N2-6 (E) - Body ground Always Below 1 Ω
    N2-5 (FPC) or A38-52 (FPC) - Body ground Always 10 kΩ or higher
    N2-4 (DI) or A38-18(DI) - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 6: Identifying Terminals Of N2 Fuel Pump ECU And A38 ECM Connectors
    G05628171Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  11. REPLACE FUEL PUMP ECU 
    1. Replace the fuel pump ECU (See REMOVAL ).
  12. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED 
    1. Check the fuel pump operation.

      OK: Malfunction has been repaired successfully. 

    NG: REPLACE ECM  (See ECM )

    OK: END 

  13. CHECK HARNESS AND CONNECTOR (CIRCUIT OPENING RELAY - EFI NO. 2 RELAY, IGN FUSE) 
    1. Remove the circuit opening relay (C/OPN) from the engine room relay block.
    2. Remove the EFI NO. 2 relay (EFI NO. 2) from the engine room relay block.
    3. Remove the IGN fuse from the engine room relay block.
    4. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    C/OPN relay (2) - IGN fuse (2) Always Below 1 Ω
    C/OPN relay (5) - EFI NO. 2 relay (3) Always Below 1 Ω
    C/OPN relay (2) or IGN fuse (2) - Body ground Always 10 kΩ or higher
    C/OPN relay (5) or EFI NO. 2 relay (3) - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 7: Identifying EFI NO. 2 Relay
    G05628172Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  14. INSPECT EFI NO. 2 RELAY (EFI NO. 2) 
    1. Remove the EFI NO. 2 relay (EFI NO. 2) from the engine room relay block.
    2. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    3-5 No battery voltage applied to terminals 1 and 2 10 kΩ or higher
    3-5 Battery voltage applied to terminals 1 and 2 Below 1 Ω

    NG: REPLACE EFI NO. 2 RELAY (EFI NO. 2) 

    Fig 8: Identifying Terminals Of EFI NO. 2 Relay
    G04976553Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  15. CHECK HARNESS AND CONNECTOR (EFI NO. 2 RELAY - INTEGRATION RELAY, BATTERY AND BODY GROUND) 
    1. Remove the EFI MAIN 2 fuse from the engine room relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      EFI MAIN 2 fuse Always Below 1 Ω
    3. Reinstall the EFI MAIN 2 fuse.
    4. Remove the EFI NO. 2 relay (EFI NO. 2) from the engine room relay block.
    5. Remove the integration relay from the engine room relay block.
    6. Disconnect the 1B integration relay connector.
    7. Disconnect the cable from the positive (+) battery terminal.
    8. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    EFI NO.2 relay (1) - 1B-4 Always Below 1 Ω
    EFI NO. 2 relay (5) -Positive (+) battery cable Always Below 1 Ω
    EFI NO. 2 relay (2) - Body ground Always Below 1 Ω
    EFI NO. 2 relay (1) or 1B-4 - Body ground Always 10 kΩ or higher
    EFI NO. 2 relay (5) or Positive (+) battery cable - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 9: Identifying Terminals Of Integration Relay
    G05627928Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: GO TO ECM POWER SOURCE CIRCUIT  (See ECM POWER SOURCE CIRCUIT )

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