LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2007 >> LS 460L >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Service Information & Circuit Tests >> 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 

      ECM (+B, +B2 VOLTAGE)

      Tester Connection Switch Condition Specified Condition
      A13-2 (+B) - E3-1 (E1) Engine switch on (IG) 11 to 14 V
      A13-1 (+B2)-E3-1 (E1) Engine switch on (IG) 11 to 14 V
      Fig 1: Identifying ECM Connector Pin Terminal
      G04942969Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

    NG: GO TO NEXT STEP 

  2. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
    1. Disconnect the E3 ECM connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open) 

      ECM - BODY GROUND

      Tester Connection Condition Specified Condition
      E3-1 (E1) - Body ground Always Below 1 Ω
      Fig 2: Identifying ECM Connector Pin Terminal
      G04942970Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    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 

      ECM (IGSW VOLTAGE)

      Tester Connection Switch Condition Specified Condition
      A14-8 (IGSW) - E3-1 (E1) Engine switch on (IG) 11 to 14 V
      Fig 3: Identifying ECM Connector Pin Terminal
      G04942971Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to step   6 

    NG: GO TO NEXT STEP 

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

      Standard resistance 

      FUSE (ECU-IG)

      Tester Connection Condition Specified Condition
      ECU-IG Always Below 1 Ω
      Fig 4: Identifying ECU-IG Fuse
      G04942972Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

    OK: GO TO NEXT STEP 

  5. INSPECT IGNITION RELAY NO. 2 (IG2) 
    1. Remove the IG2 relay from the engine room No. 2 junction block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      IGNITION RELAY NO. 2 (IG2)

      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 5: Identifying IG2 Relay
      G04942973Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE IGNITION RELAY NO. 2 (IG2) (See  IGNITION RELAY NO. 2   ) 

    OK: GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START  (See POWER SOURCE MODE DOES NOT CHANGE )

  6. 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 

      ECM (MREL VOLTAGE)

      Tester Connection Switch Condition Specified Condition
      A14-3 (MREL) - E3-1 (E1) Engine switch on (IG) 9 to 14 V
      Fig 6: Identifying ECM Connector Pin Terminal
      G04942974Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE ECM (See  REMOVAL   ) 

    OK: GO TO NEXT STEP 

  7. CHECK FUSE (EFI MAIN2) 
    1. Remove the EFI MAIN2 fuse from the engine room No. 2 relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      FUSE (EFI MAIN2)

      Tester Connection Condition Specified Condition
      EFI MAIN2 Always Below 1 Ω
      Fig 7: Identifying EFI MAIN2 Fuse
      G04942975Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

    OK: GO TO NEXT STEP 

  8. INSPECT EFI RELAY (EFI MAIN2) 
    1. Remove the EFI MAIN2 relay from the engine room No. 2 relay block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      EFI RELAY (EFI MAIN2)

      Tester Connection Condition Specified Condition
      3-5 When no battery voltage applied to terminals 1 and 2 10 kΩ or higher
      When battery voltage applied to terminals 1 and 2 Below 1 Ω
      Fig 8: Identifying EFI MAIN2 Relay From Engine Room No. 2 Relay Block
      G04942976Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE EFI RELAY (EFI MAIN2) (See  EFI RELAY   ) 

    OK: GO TO NEXT STEP 

  9. CHECK HARNESS AND CONNECTOR (EFI RELAY (EFI MAIN2) - ECM, BODY GROUND) 
    1. Check the harness and the connectors between the integration relay and the ECM.
      1. Remove the EFI MAIN2 relay from the engine room No. 2 relay block.
      2. Disconnect the A14 ECM connector.
      3. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        EFI RELAY (EFI MAIN2) - ECM, BODY GROUND (CHECK FOR OPEN)

        Tester Connection Condition Specified Condition
        EFI MAIN2 relay (1) - A14-3 (MREL) Always Below 1 Ω

        Standard resistance (Check for short) 

        EFI RELAY (EFI MAIN2) - ECM, BODY GROUND (CHECK FOR SHORT)

        Tester Connection Condition Specified Condition
        EFI MAIN2 relay (1) or A14-3 (MREL) - Body ground Always 10 kΩ or higher
    2. Check the harness and the connectors between the EFI MAIN2 relay and body ground.
      1. Remove the EFI MAIN2 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) 

        EFI MAIN2 - BODY GROUND (CHECK FOR OPEN)

        Tester Connection Condition Specified condition
        EFI MAIN2 relay (2) - Body ground Always Below 1 Ω
        Fig 9: Identifying A14 ECM Connector Pin Terminal
        G04942977Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: CHECK AND REPAIR HARNESS OR CONNECTOR (TERMINAL +B OF ECM - BATTERY POSITIVE TERMINAL) 

scientia non olet · About LEMON Manuals