LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2008 >> LX 570 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - System Descriptions And Testing, On-Vehicle Inspection, Removal And Installation >> ECM Power Source Circuit >> Inspection Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Inspection Procedure

  1. INSPECT FUSES (IG2 MAIN, EFI MAIN AND IGN) 
    1. Remove the IG2 MAIN fuse, EFI MAIN fuse and IGN fuse from the engine room 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
    IG2 MAIN fuse Always Below 1 Ω
    EFI MAIN fuse Always Below 1 Ω
    IGN fuse Always Below 1 Ω

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

    OK: Go to Next Step 

    Fig 1: Identifying IG2 Main, EFI Main And IGN Fuses
    G05628153Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. INSPECT RELAY (IG2, EFI) 
    1. Remove the integration relay from the engine room 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
    1C-1 - 1B-8 No battery voltage applied to terminals 1B-6 and 1B-7 10 kΩ or higher
    1C-1 - 1B-8 Battery voltage applied to terminals 1B-6 and 1B-7 Below 1 Ω
    1C-1 - 1B-4 No battery voltage applied to terminals 1B-2 and 1B-3 10 kΩ or higher
    1C-1 - 1B-4 Battery voltage applied to terminals 1B-2 and 1B-3 Below 1 Ω

    NG: REPLACE RELAY 

    Fig 2: Identifying Terminals Of Integration Relay
    G05757788Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  3. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
    1. Disconnect the C53 ECM connector.
    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
    C53-81 (E1) - Body ground Always Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 3: Identifying Terminals Of C53 ECM Connector
    G05628155Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  4. CHECK HARNESS AND CONNECTOR (RELAY BLOCK - ECM, MAIN BODY ECU, BATTERY) 
    1. Disconnect the A38 ECM connector.
    2. Disconnect the E2 main body ECU connector.
    3. Disconnect the cable from the battery positive (+) terminal.
    4. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    A38-28 (IGSW) - 1B-8 Always Below 1 Ω
    1B-7 - Body ground Always Below 1 Ω
    Positive (+) battery cable-1C-1 Always Below 1 Ω
    E2-11 (IG2D) - 1B-6 Always Below 1 Ω
    A38-28 (IGSW) or 1B-8-Body ground Always 10 kΩ or higher
    Positive (+) battery cable or 1C-1 - Body ground Always 10 kΩ or higher
    E2-11 (IG2D) or 1B-6 - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 4: Identifying Terminals Of A38 ECM Connector
    G05628156Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to Next Step 

  5. INSPECT ECM (IGSW VOLTAGE) 
    1. Disconnect the A38 and C53 ECM connectors.
    2. Turn the engine switch on (IG).
    3. 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
    A38-28 (IGSW) - C53-81 (E1) Engine switch on (IG) 11 to 14 V

    0K :  Go to step  7

    NG:  Go to step  6

    Fig 5: Identifying Terminals Of A38 And C53 ECM Connectors
    G05628157Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  6. CHECK SMART ACCESS SYSTEM WITH PUSH-BUTTON START (POWER SOURCE MODE DOES NOT CHANGE) 
    1. Check the smart access system with push-button start (See POWER SOURCE MODE DOES NOT CHANGE ).

    NG: REPAIR SMART ACCESS SYSTEM WITH PUSH-BUTTON START 

    OK: Go to Next Step 

  7. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM, BATTERY AND BODY GROUND) 
    1. Disconnect the A38 ECM connector.
    2. Disconnect the cable from the battery positive terminal.
    3. Remove the integration relay from the engine room relay block.
    4. Disconnect the integration relay connector.
    5. Measure the resistance according to the value(s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    A38-3(+B) - 1B-4 Always Below 1 Ω
    A38-2(+B2) - 1B-4 Always Below 1 Ω
    A38-34(MREL) - 1B-2 Always Below 1 Ω
    1C-1 - Positive (+) battery cable Always Below 1 Ω
    1B-3 - Body ground Always Below 1 Ω
    A38-3 (+B) or 1B-4 - Body ground Always 10 kΩ or higher
    A38-2 (+B2) or 1B-4 - Body ground Always 10 kΩ or higher
    A38-34 (MREL) or 1B-2-Body ground Always 10 kΩ or higher
    1C-1 or Positive (+) battery cable - Body ground Always 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 6: Identifying Terminals Of A38 ECM Connector
    G05628158Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: REPLACE ECM  (See ECM )

scientia non olet · About LEMON Manuals