LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2008 >> LS 460 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - System & Circuit Troubleshooting, Component Inspection And R & I >> 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 the fuel pressure (see ON-VEHICLE INSPECTION ).

      HINT:

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

    OK: Go to step  10

    NG: Go to next step. 

  2. PERFORM ACTIVE TEST BY TECHSTREAM (OPERATE CIRCUIT OPENING RELAY (C/ OPN)) 
    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 / Active Test / Activate the Fuel Pump Speed Control
    4. Check whether operating sounds can be heard while operating the relay using the Techstream.

      OK: Operating sounds can be heard from relay. 

    OK: Go to step  5

    NG: Go to next step. 

  3. INSPECT CIRCUIT OPENING RELAY (C/OPN) 
    1. Remove the C/OPN relay from the engine room No. 2 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 When no battery voltage applied to terminals 1 and 2 10 kΩ or higher
      3 - 5 When battery voltage applied to terminals 1 and 2 Below 1 Ω
      Fig 1: Identifying Terminals Of C/OPN Relay
      G04942983Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE CIRCUIT OPENING RELAY (C/ OPN)  (See ON-VEHICLE INSPECTION  )

    OK: Go to next step. 

  4. 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 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Switch Condition Specified Condition
      A14-5 (FC) - E3-1 (E1) Engine switch on (IG) 11 to 14 V
      Fig 2: Identifying Terminals Of E3 And A14 ECM Connectors
      G04942984Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: REPLACE ECM  (See REMOVAL  )

    NG: CHECK AND REPLACE HARNESS OR CONNECTOR (CIRCUIT OPENING RELAY (C/OPN) - ECM, EFI-B FUSE) 

  5. INSPECT ECM POWER SOURCE CIRCUIT 
    1. Inspect the ECM power source circuit (see ECM POWER SOURCE CIRCUIT  ).

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step. 

  6. INSPECT FUEL PUMP RELAY (F/PMP)  (See INSPECTION PROCEDURE )

    NG: REPLACE FUEL PUMP RELAY (F/PMP)  (See ON-VEHICLE INSPECTION  )

    OK: Go to next step. 

  7. INSPECT FUEL PUMP ASSEMBLY 
    1. Inspect the fuel pump resistance.
      1. Measure the resistance according to the value(s) in the table below.

        Standard Resistance 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        4-5 20°C (68°F) 0.2 to 3.0 Ω
        Fig 3: Identifying Terminals Of Fuel Pump Assembly Connector
        G04942985Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Inspect the fuel pump operation.
      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 ASSEMBLY  (See REMOVAL )

    OK: Go to next step. 

  8. CHECK HARNESS AND CONNECTOR (FUEL PUMP - FUEL PUMP RELAY (F/PMP), BODY GROUND) 
    1. Check the harness and connector between the fuel pump and F/PMP relay.
      1. Disconnect the S11 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) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        S11-4 - F/PMP relay (3) Always Below 1 Ω

        Standard Resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        S11-4 or F/PMP relay (3) - Body ground Always 10 kΩ or higher
      4. Reconnect the fuel pump connector.
      5. Reinstall the F/PMP relay.
    2. Check the harness and connector between the fuel pump and body ground.
      1. Disconnect the S11 fuel pump connector.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        S11-5 - Body ground Always Below 1 Ω
        Fig 4: Identifying Terminals Of S11 Fuel Pump Connector
        G04942986Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      3. Reconnect the fuel pump connector.

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step. 

  9. CHECK HARNESS AND CONNECTOR (CIRCUIT OPENING RELAY (C/OPN) - FUEL PUMP RELAY (F/PMP)) 
    1. Remove the C/OPN relay and 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 (Check for open) 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      C/OPN relay (3) - F/PMP relay (4) Always Below 1 a

      Standard Resistance (Check for short) 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      C/OPN relay (3) or F/ PMP relay (4) - Body ground Always 10 kΩ or higher
      Fig 5: Identifying F/PMP Relay
      G04942987Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE ENGINE ROOM NO. 2 RELAY BLOCK, JUNCTION BLOCK 

    OK: CHECK AND REPAIR HARNESS OR CONNECTOR (EFI RELAY (EFI MAIN) - CIRCUIT OPENING RELAY (C/OPN)) 

  10. INSPECT FUEL PUMP RELAY (F/PMP)  (See INSPECTION PROCEDURE )

    NG: REPLACE FUEL PUMP RELAY (F/PMP)  (See ON-VEHICLE INSPECTION  )

    OK: Go to next step. 

  11. INSPECT FUEL PUMP RESISTOR (RESISTANCE) 
    1. Inspect the fuel pump resistor resistance.
    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
      1 - 2 20°C (68°F) 0.941 to 0.999 Ω
      Fig 6: Measuring Resistance Between Fuel Pump Resistor Terminals
      G04942988Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE FUEL PUMP RESISTOR  (See REMOVAL )

    OK: Go to next step. 

  12. CHECK HARNESS AND CONNECTOR (FUEL PUMP RESISTOR - FUEL PUMP RELAY (F/PMP), FUEL PUMP) 
    1. Check the harness and connector between the fuel pump relay and fuel pump resistor.
      1. Remove the F/PMP relay from the engine room No. 2 relay block.
      2. Disconnect the A16 fuel pump resistor connector.
      3. Measure the resistance according to the value(s) in the table below.

        Standard Resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        F/PMP relay (4) - A16-1 Always Below 1 Ω

        Standard Resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        F/PMP relay (4) or A16-1 - Body ground Always 10 kΩ or higher
      4. Reinstall the F/PMP relay.
      5. Reconnect the fuel pump resistor connector.
    2. Check the harness and connector between the fuel pump resistor and fuel pump.
      1. Disconnect the A16 fuel pump resistor connector.
      2. Disconnect the S11 fuel pump connector.
      3. Measure the resistance according to the value(s) in the table below.

        Standard Resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        A16-2-S11-4 Always Below 1 Ω

        Standard Resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION CHART

        Tester Connection Condition Specified Condition
        A16-2 or S11-4-Body ground Always 10 kΩ or higher
        Fig 7: Identifying Fuel Pump Relays And Terminals Of A16 & S11 Connectors
        G04942989Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      4. Reconnect the fuel pump resistor connector.
      5. Reconnect the fuel pump connector.

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

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

scientia non olet · About LEMON Manuals