LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2008 >> GS 460 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (1UR-FSE) - Circuit Tests And Repair Information >> ECM Power Source Circuit >> Inspection Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Inspection Procedure

  1. INSPECT ECM (+B, +B2 VOLTAGE) 
    1. Turn the engine switch on (IG).
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Switch Condition Specified Condition
      A7-2 (+B) - E86-1 (E1) Engine switch on (16) 11 to 14 V
      A7-1 (+B2) - E86-1 (E1) Engine switch on (IG) 11 to 14 V

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

    Fig 1: Inspecting ECM (+B, +B2 Voltage)
    G05803993Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
    1. Disconnect the ECM connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open) 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Condition Specified Condition
      E86-1 (E1) - Body ground Always Below 1 Ω
    3. Reconnect the ECM connector.

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 2: Disconnecting E86 ECM Connector
    G05803994Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

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

      Standard voltage 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Switch Condition Specified Condition
      A6-8 (IGSW) - E86-1 (E1) Engine switch on (IG) 11 to 14 V

    OK:  Go to step  7

    Fig 3: Inspecting ECM (IGSW Voltage)
    G05803995Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to next step 

  4. CHECK FUSE (IGN FUSE) 
    1. Remove the IGN fuse from the cowl side junction block RH.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Condition Specified Condition
      IGN fuse Always Below 1 Ω
    3. Reinstall the fuse.

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

    Fig 4: Identifying IGN Fuse
    G05285288Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  5. INSPECT IGNITION RELAY NO. 2 (IG2) 
    1. Remove the IG2 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 CONNECTIONS SPECIFIED CONDITIONS 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
    3. Reinstall the relay.

    NG: REPLACE IGNITION RELAY NO. 2 (IG2) 

    Fig 5: Ignition Relay No. 2 (IG2) Circuit Diagram
    G04967794Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (ECM - IG2 RELAY) 
    1. Remove the IG2 relay from the engine room No. 2 relay block.
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Condition Specified Condition
      IG2 relay (3) - A6-8 (IGSW) Always Below 1 Ω
    4. Reinstall the IG2 relay.
    5. Reconnect the ECM connector.

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 6: Checking Harness And Connector (ECM - IG2 Relay)
    G05803998Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START  (See HOW TO PROCEED WITH TROUBLESHOOTING )

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

      Standard voltage 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Switch Condition Specified Condition
      A6-3 (MREL) - E86-1 (E1) Engine switch on (IG) 11 to 14 V

    NG: REPLACE ECM  (See REMOVAL  )

    Fig 7: Inspecting ECM (MREL Voltage)
    G05803999Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  8. CHECK FUSE (EFI FUSE) 
    1. Remove the EFI fuse from the engine room No. 2 junction block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Condition Specified Condition
      EFI fuse Always Below 1 Ω
    3. Reinstall the fuse.

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

    Fig 8: Identifying EFI Fuse
    G05751794Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  9. INSPECT INTEGRATION RELAY (EFI MAIN 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 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Condition Specified Condition
      2C-1 - 2A-8 When no battery voltage applied terminals 2A-6 and 2A-7 10 kΩ or higher
      When battery voltage applied to terminals 2A-6 and 2A-7 Below 1 Ω (When battery voltage applied to terminals 2A-6 and 2A-7)
    3. Reinstall the integration relay.

    NG: REPLACE INTEGRATION RELAY 

    Fig 9: Identifying Integration Relay
    G05803755Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  10. CHECK HARNESS AND CONNECTOR (EFI MAIN RELAY - ECM AND BODY GROUND) 
    1. Check the harness and the connectors between the integration relay and the ECM.
      1. Remove the integration relay from the engine room No. 2 junction block.
      2. Disconnect the ECM connector.
      3. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

        Tester Connection Condition Specified Condition
        2A-6 - A6-3 (MREL) Always Below 1 Ω

        Standard resistance (Check for short) 

        TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

        Tester Connection Condition Specified Condition
        2A-6 or A6-3 (MREL) - Body ground Always 10 kΩ or higher
    2. Check the harness and the connectors between the integration relay and body ground.
      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 (Check for open) 

        TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

        Tester Connection Condition Specified condition
        2A-7 - Body ground Always Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 10: Checking Harness And Connector (EFI Main Relay - ECM And Body Ground)
    G05804002Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  11. CHECK HARNESS AND CONNECTOR (EFI MAIN RELAY - ECM) 
    1. Remove the integration relay from the engine room No. 2 relay block.
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTIONS SPECIFIED CONDITIONS CHART

      Tester Connection Condition Specified Condition
      2A-8 - A7-2(+B) Always Below 1 Ω
      2A-8 - A7-1 (+B) Always Below 1 Ω
    4. Reinstall the integration relay.
    5. Reconnect the ECM connector.

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI MAIN RELAY - ECM) 

    Fig 11: Checking Harness And Connector (EFI Main Relay - ECM)
    G05804003Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - INTEGRATION RELAY) 

scientia non olet · About LEMON Manuals