LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2008 >> GS 350 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - System And Circuit Testing, On-Vehicle Inspection, Removal, Inspection & Installation >> Fuel Pump Control Circuit >> Inspection Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Inspection Procedure

  1. CHECK FUEL PUMP OPERATION 
    1. Check if there is pressure in the fuel inlet hose.

      HINT:

      If there is fuel pressure, you will hear the sound of fuel flowing.

    OK :  Go to step  12

    NG : Go to next step 

  2. PERFORM ACTIVE TEST USING TECHSTREAM (OPERATE C/OPN RELAY) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG) and turn the Techstream on.
    3. Select the following menu items: Powertrain/Engine and ECT/Active Test/Control the Fuel Pump/Speed.
    4. Check the operation of the relay while operating it using the Techstream.

      OK: 

      Operating noise can be heard from the relay. 

    OK :  Go to step  8

    NG : Go to next step 

  3. INSPECT ECM POWER SOURCE CIRCUIT 
    1. Check the ECM power source circuit (See ECM POWER SOURCE CIRCUIT  ).

      Standard voltage: 

      9 to 14 V 

    NG : REPAIR OR REPLACE POWER SOURCE CIRCUIT 

    OK : Go to next step 

  4. INSPECT FUSE (F/PMP FUSE) 
    1. Remove the F/PMP fuse from the engine room No. 2 relay block, junction block.
    2. Measure the resistance of the F/PMP fuse.

      Standard resistance: 

      Below 1 Ω 

    NG : CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE 

    Fig 1: Identifying F/PMP Fuse From Engine Room No. 2 Relay Block
    G05285298Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK : Go to next step 

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

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      2B-4 - 2C-1 10 kΩ or higher
      2B-4 - 2C-1 Below 1 Ω (when battery voltage applied to terminals 2B-3 and 2B-2)

    NG : REPLACE INTEGRATION RELAY 

    Fig 2: Identifying Integration Relay
    G05285299Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK : Go to next step 

  6. INSPECT INTEGRATION RELAY (C/OPN RELAY) 
    1. Remove the integration relay from the engine room No. 2 junction block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      2B-6 - 2B-8 10 kΩ or higher
      2B-6 - 2B-8 Below 1 Ω (when battery voltage applied to terminals 2B-6 and 2B-7)

    NG : REPLACE INTEGRATION RELAY 

    Fig 3: Identifying Integration Relay
    G05285299Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK : Go to next step 

  7. INSPECT ECM (FC VOLTAGE) 
    1. Turn the engine switch on (IG).
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      STANDARD VOLTAGE SPECIFICATION

      Tester Connection Specified Condition
      A6-14 (FC) - E7-7 (E1) 9 to 14 V

    OK : REPLACE ECM 

    Fig 4: Identifying E7 And A6 ECM Connectors
    G05285301Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG : CHECK AND REPAIR HARNESS AND CONNECTOR (ECM - C/OPN RELAY) 

  8. INSPECT F/PMP RELAY 
    1. Remove the F/PMP relay from the engine room No. 2 relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      3-4 10 kΩ or higher
      3-4 Below 1 Ω (when battery voltage applied to terminals 1 and 2)
      Fig 5: Inspecting F/Pump Relay
      G05285125Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG : REPLACE F/PMP RELAY 

    OK : Go to next step 

  9. INSPECT FUEL PUMP 
    1. Inspect fuel pump resistance.
      1. Measure the resistance between terminals 4 and 5.

        Standard resistance: 

        0.2 to 3.0 Ω at 20°C (68°F) 

    2. Inspect fuel pump operation.
      Fig 6: Identifying Fuel Pump Connector
      G05285303Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Apply battery voltage to both terminals. Check that the pump operates.
        NOTE:
        • These tests must be done quickly (within 10 seconds) to prevent the coil from burning out.
        • Keep the fuel pump as far away from the battery as possible.
        • Always turn the voltage on and off on the battery side, not the fuel pump side.

    NG : REPLACE FUEL PUMP 

    OK : Go to next step 

  10. CHECK HARNESS AND CONNECTOR (FUEL PUMP - F/PMP RELAY) 
    1. Check the harness and the connectors between the fuel pump and the F/PMP relay.
      1. Disconnect the fuel pump connector.
      2. Remove the F/PMP relay from the engine room No. 2 relay block.
      3. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        STANDARD RESISTANCE SPECIFICATION

        Tester Connection Specified Condition
        Fuel pump (V11-4) - F/PMP relay (4) Below 1 Ω

        Standard resistance (Check for short) 

        STANDARD RESISTANCE SPECIFICATION

        Tester Connection Specified Condition
        Fuel pump (V11-4) or F/PMP (4) - Body ground 10 kΩ or higher
    2. Check the harness and the connectors between the fuel pump and body ground.
      1. Disconnect the fuel pump connector.
      2. Measure the resistance according to the value(s) in the table below.
        Fig 7: Identifying V11 Fuel Pump Connector And F/Pump Relay
        G05803502Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        Standard resistance (Check for open) 

        STANDARD RESISTANCE SPECIFICATION

        Tester Connection Specified Condition
        Fuel pump (V11-5) - Body ground 10 kΩ or higher

    NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK : Go to next step 

  11. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - F/PMP RELAY) 
    1. Remove the integration relay from the engine room No. 2 junction block.
    2. Remove the F/PMP relay from the engine room No. 2 junction block.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open) 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      Integration relay (2B-8) - F/PMP relay (1) Below 1 Ω
      Integration relay (2B-8) - F/PMP relay (3) Below 1 Ω

      Standard resistance (Check for short) 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      Circuit opening relay (2B-8) or F/PMP relay (1) - Body ground 10 kΩ or higher
      Circuit opening relay (2B-8) or F/PMP relay (3) - Body ground 10 kΩ or higher

    NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 8: Identifying Integration Relay From Engine Room No. 2 Junction Block
    G05285305Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK : REPAIR OR REPLACE INTEGRATION RELAY 

  12. INSPECT F/PMP RELAY 
    1. Remove the F/PMP relay from the engine room No. 2 relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      3-4 10 kΩ or higher
      3-4 Below 1 Ω (when battery voltage applied to terminals 1 and 2)
      Fig 9: Inspecting F/Pump Relay
      G05285125Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG : REPLACE F/PMP RELAY 

    OK : Go to next step 

  13. INSPECT FUEL PUMP RESISTOR 
    1. Measure the resistance of the fuel pump resistor.

      Standard resistance: 

      0.30 to 0.34 Ω at 20°C (68°F) 

    NG : REPLACE FUEL PUMP RESISTOR 

    Fig 10: Measuring Resistance Of Fuel Pump Resistor
    G04962581Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK : Go to next step 

  14. CHECK HARNESS AND CONNECTOR (F/PMP RELAY - FUEL PUMP RESISTOR) 
    1. Check the harness and the connectors between the F/PMP relay and the fuel pump resistor.
      1. Remove the F/PMP relay from the engine room No. 2 relay block.
      2. Disconnect the fuel pump resistor connector.
      3. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        STANDARD RESISTANCE SPECIFICATION

        Tester Connection Specified Condition
        F/PMP relay (4) - Fuel pump resistor (A45-2) Below 1 Ω
        F/PMP relay (3) - Fuel pump resistor (A45-1) Below 1 Ω

        Standard resistance (Check for short) 

        STANDARD RESISTANCE SPECIFICATION

        Tester Connection Specified Condition
        Fuel pump relay (4) or Fuel pump resistor (A45-2) - Body ground 10 kΩ or higher
        Fuel pump relay (3) or Fuel pump resistor (A45-1) - Body ground 10 kΩ or higher

    OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE 

    Fig 11: Identifying Fuel Pump Resistor Connector
    G05803506Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

scientia non olet · About LEMON Manuals