LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2008 >> LS 600hL >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - Circuit Tests, Component Removal, Inspection & Installation >> 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 power switch ON (IG).
    2. Measure the voltage according to the value (s) in the table below.

      Standard voltage 

      STANDARD VOLTAGE

      Tester Connection Switch Condition Specified Condition
      A13-2 (+B) - E3-1 (E1) Power switch ON (IG) 11 to 14 V
      A13-1 (+B2) - E3-1 (E1) Power switch ON (IG) 11 to 14 V
      Fig 1: Identifying E3 And A13 ECM Connector Terminal
      G05771165Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to step 2 

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

  2. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
    1. Disconnect the E3 ECM connector.
      2. Fig 2: Identifying E3 ECM Connector Terminal
      G05771166Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value (s) in the table below.

      Standard resistance (Check for open) 

      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      E3-1 (E1) - Body ground Always Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

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

      Standard voltage 

      STANDARD VOLTAGE

      Tester Connection Switch Condition Specified Condition
      A14-8 (IGSW) - E3-1 (E1) Power switch ON (IG) 11 to 14 V
      Fig 3: Identifying E13 And A14 ECM Connector Terminal
      G05771167Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK:  Go to step  6

    NG: Go to step 4 

  4. INSPECT FUSE (ECU-IG) 
    1. Remove the ECU-IG fuse from the engine room No. 2 junction block
      2. Fig 4: Identifying Engine Room No. 2 Junction Block
      G04942972Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value (s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      ECU-IG Always Below 1 Ω

    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. Inspect the IG2 relay (see ON-VEHICLE INSPECTION  ).

    NG: REPLACE IGNITION RELAY NO. 2 (IG2)  (See ON-VEHICLE INSPECTION  )

    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 power switch ON (IG).
    2. Measure the voltage according to the value (s) in the table below.

      Standard voltage 

      STANDARD VOLTAGE

      Tester Connection Switch Condition Specified Condition
      A14-3 (MREL) - E3-1 (E1) Power switch ON (IG) 11 to 14 V
      Fig 5: Identifying E13 And A14 ECM Connector Terminal
      G05771169Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE ECM  (See REMOVAL  )

    OK: Go to next step 

  7. INSPECT FUSE (EFI MAIN2) 
    1. Remove the EFI MAIN2 fuse from the engine room No. 2 relay block.
      2. Fig 6: Identifying Engine Room No. 2 Relay Block And EFI MAIN2 Fuse
      G04942975Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value (s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      EFI MAIN2 Always Below 1 Ω

    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. Inspect the EFI MAIN2 relay (see ON-VEHICLE INSPECTION  ).

    NG: REPLACE EFI RELAY (EFI MAIN2)  (See ON-VEHICLE INSPECTION  )

    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 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) 

        STANDARD RESISTANCE

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

        Standard resistance (Check for short) 

        STANDARD RESISTANCE

        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. Fig 7: Identifying Engine Room No. 2 Relay Block And A14 Connector Terminal
        G05771171Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      2. Measure the resistance according to the value (s) in the table below.

        Standard resistance (Check for open) 

        STANDARD RESISTANCE

        Tester Connection Condition Specified condition
        EFI MAIN2 relay (2) - Body ground Always Below 1 Ω

    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