LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2008 >> GS 450h >> 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. PERFORM ACTIVE TEST USING TECHSTREAM (FUEL PUMP/SPD) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power 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 the fuel pump operating sound occurs when perform the Active Test on the Techstream.

    OK: Fuel pump operating sound occurs. 

    OK:  Go to step  10

    NG: Go to next step 

  2. INSPECT INTEGRATION RELAY 
    1. Remove the integration relay (Unit A) from the engine room No. 1 junction block.
    2. Inspect the F/PMP fuse.
      1. Remove the F/PMP fuse from the integration relay.
      2. Measure the resistance of the F/PMP fuse.

        Standard resistance: Below 1 Ω 

      3. Reinstall the F/PMP fuse.
    3. Inspect the EFI NO.2 and C/OPN relay.
      1. Measure the resistance of the EFI NO.2 and C/OPN relays.

      Standard resistance: 

      EFI NO.2 relay 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Specified Condition
      1R-1 - 1S-7 10 kΩ or higher
      Below 1 Ω (Apply battery voltage between terminals 1T-8 and 1S-3)
      Fig 1: Identifying Integration Relay (Unit A)
      G05302508Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      C/OPN relay 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Specified Condition
      1R-1 - 1S-8 10 kΩ or higher
      Below 1 Ω (Apply battery voltage between terminals 1T-8 and 1S-3,1R-1 and 1S-7)
    4. Reinstall the integration relay.

    NG: REPLACE INTEGRATION RELAY 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM, INTEGRATION RELAY - FUEL PUMP RESISTOR) 
    1. Remove the integration relay (Unit A) from the engine room No. 1 junction block.
    2. Disconnect the A53 ECM connector.
    3. Disconnect the A45 fuel pump resistor connector.
    4. Measure the resistance.

      Standard resistance (Check for open) 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Specified Condition
      Engine room No. 1 junction block (1S-7) - FC (A53-7) Below 1 Ω
      Engine room No. 1 junction block (1S-8) - A45-1 Below 1 Ω

      Standard resistance (Check for short) 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Specified Condition
      Engine room No. 1 junction block (1S-7) or FC (A53-7) - Body ground 10 kΩ or higher
      Engine room No. 1 junction block (1S-8) or A45-1 - Body ground 10 kΩ or higher
    5. Reinstall the integration relay.
    6. Reconnect the ECM connector.
    7. Reconnect the fuel pump resistor.
      8. Fig 2: Identifying Integration Relay (Unit A) And A53 ECM Connector Terminals
      G05302509Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  4. INSPECT ECM POWER SOURCE CIRCUIT 

    NG: REPAIR OR REPLACE POWER SOURCE CIRCUIT COMPONENTS 

    OK: Go to next step 

  5. INSPECT F/PMP RELAY 
    1. Remove the F/PMP relay from the engine room No. 1 relay block.
    2. Measure the resistance of the F/PMP relay.

    Standard resistance 

    TESTER CONNECTION AND SPECIFIED CONDITION

    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 3: Inspecting F/PMP Relay
    G05302510Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE F/PMP RELAY 

    OK: Go to next step 

  6. INSPECT FUEL PUMP RESISTOR 
    1. Remove the fuel pump resistor.
    2. Measure the resistance of the fuel pump resistor.
      3. Fig 4: Inspecting Fuel Pump Resistor
      G04962581Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    Standard resistance: 0.30 to 0.34 Ω at 20°C (68°F) 

    NG: REPLACE FUEL PUMP RESISTOR 

    OK: Go to next step 

  7. INSPECT FUEL PUMP FOR LOW PRESSURE SIDE 
    1. Remove the rear seat cushion.
    2. Disconnect the V11 fuel pump connector.
    3. 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) 

    4. Inspect fuel pump operation.
    Fig 5: Identifying V11 Fuel Pump Connector Terminals
    G05302512Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Apply battery voltage to both the 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 FOR LOW PRESSURE SIDE 

    OK: Go to next step 

  8. CHECK HARNESS AND CONNECTOR (F/PMP RELAY - ECM, F/PMP RELAY - FUEL PUMP RESISTOR) 
    1. Remove the F/PMP relay from the engine room No. 1 relay block.
    2. Disconnect the A53 ECM connector.
    3. Disconnect the A45 fuel pump resistor connector.
    4. Measure the resistance of the wire harness side connectors.

    Standard resistance (Check for open) 

    TESTER CONNECTION AND SPECIFIED CONDITION

    Tester Connection Specified Condition
    F/PMP relay (2) - FPR (A53-6) Below 1 Ω
    F/PMP relay (1) - A45-1 Below 1 Ω
    F/PMP relay (3) - A45-1 Below 1 Ω

    Standard resistance (Check for short) 

    TESTER CONNECTION AND SPECIFIED CONDITION

    Tester Connection Specified Condition
    F/PMP relay (2) or FPR (A53-6) - Body ground 10 kΩ or higher
    F/PMP relay (1) or A45-1 - Body ground 10 kΩ or higher
    F/PMP relay (3) or A45-1 - Body ground 10 kΩ or higher
    Fig 6: Identifying F/PMP Relay And A53 ECM Connector Terminals
    G05302513Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  9. CHECK HARNESS AND CONNECTOR (F/PMP RELAY - FUEL PUMP, FUEL PUMP RESISTOR - FUEL PUMP, FUEL PUMP - BODY GROUND) 
    1. Remove the F/PMP relay from the engine room No. 1 relay block.
    2. Disconnect the V11 fuel pump connector.
    3. Disconnect the A45 fuel pump resistor connector.
    4. Measure the resistance.

      Standard resistance (Check for open) 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Specified Condition
      F/PMP relay (4) - V11-4 Below 1 Ω
      A45-2 - V11-4 Below 1 Ω
      V11-5 - Body ground Below 1 Ω

      Standard resistance (Check for short) 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Specified Condition
      F/PMP relay (4) or V11-4 - Body ground 10 kΩ or higher
      A45-2 or V11-4 - Body ground 10 kΩ or higher
    5. Reconnect the fuel pump resistor connector.
    6. Reconnect the fuel pump connector.
    7. Reinstall the F/PMP relay.
      8. Fig 7: Identifying F/PMP Relay And A45 Connector Terminals
      G05302514Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: REPLACE ECM 

  10. READ VALUE USING TECHSTREAM (ENGINE SPEED) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG) and turn the Techstream on.
    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Engine Speed.
    4. Read the values displayed on the Techstream while cranking.

      OK: Values are displayed continuously. 

      NG: REPAIR OR REPLACE CRANKSHAFT POSITION SENSOR 

      OK: REPLACE ECM 

scientia non olet · About LEMON Manuals