LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2007 >> GX 470 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - System And Circuit Testing, On-Vehicle Inspection, Removal, Inspection, Installation >> ECM Power Source Circuit >> Inspection Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Inspection Procedure

  1. CHECK ECM (+B VOLTAGE) 
    Fig 1: Identifying E7 ECM Connector Terminal & E9 ECM Connector Terminal
    G05264269Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Turn the ignition switch ON.
    2. Measure the voltage of the ECM connectors.

      Standard voltage 

      VOLTAGE SPECIFICATION

      Tester Connection Specified Condition
      +B (E9-1) - E1 (E7-1) 9 to 14 V

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

    NG: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
      Fig 2: Identifying E7 ECM Connector Terminal
      G05264270Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Disconnect the E7 ECM connector.
    2. Measure the resistance of the wire harness side connector.

      Standard resistance 

      RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      E1 (E7-1) - Body ground Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. CHECK ECM (IGSW VOLTAGE) 
    Fig 3: Identifying E7 ECM Connector Terminal & E9 ECM Connector Terminal
    G05264271Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Turn the ignition switch ON.
    2. Measure the voltage of the ECM connectors.

      Standard voltage 

      VOLTAGE SPECIFICATION

      Tester Connection Specified Condition
      IGSW (E9-9) - E1 (E7-1) 9 to 14 V

    OK:  Go to step  6

    NG: Go to next step 

  4. INSPECT FUSE (IGN) 
    Fig 4: Identifying IGN Fuse To Driver Side J/B
    G04968173Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Remove the IGN fuse from the driver side J/B.
    2. Measure the resistance of the IGN fuse.

      Standard resistance: 

      Below 1 Ω 

    NG: REPLACE FUSE 

    OK: Go to next step 

  5. INSPECT IGNITION SWITCH ASSEMBLY 
    1. Remove the lower finish panel.
      2. Fig 5: Identifying I18 Ignition Switch Connector Terminal
      G04967994Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    2. Disconnect the I18 ignition switch connector.
    3. Measure the resistance of the ignition switch.

      Standard resistance 

      RESISTANCE SPECIFICATION

      Switch position Tester Connection Specified Condition
      LOCK All Terminals 10 kΩ or higher
      ACC 2-3 Below 1 Ω
      ON 2-3, 2-4 6-7
      START 1-2, 2-4 6-7, 6-8
    4. Reconnect the ignition switch connector.

    NG: REPLACE IGNITION SWITCH ASSEMBLY 

    OK: REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IGNITION SWITCH, IGNITION SWITCH - ECM) 

  6. CHECK ECM (MREL VOLTAGE) 
    Fig 6: Identifying ECM Connector Terminal
    G05264274Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Turn the ignition switch ON.
    2. Measure the voltage of the ECM connectors.

      Standard voltage 

      VOLTAGE SPECIFICATION

      Tester Connection Specified Condition
      MREL (E9-8) - E1 (E7-1) 9 to 14 V

    NG: REPLACE ECM 

    OK: Go to next step 

  7. INSPECT FUSE (EFI) 
    Fig 7: Identifying EFI Fuse
    G04968176Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Remove the EFI fuse from the engine room R/B.
    2. Measure the resistance of the EFI fuse.

      Standard resistance: 

      Below 1 Ω 

    NG: REPLACE FUSE 

    OK: Go to next step 

  8. INSPECT EFI RELAY (Marking: EFI OR ECD) 
    Fig 8: Identifying EFI Relay Terminals
    G04967794Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Remove the EFI relay from the engine room junction block.
    2. Measure the resistance of the EFI relay.

      Standard resistance 

      RESISTANCE SPECIFICATION

      Terminal Connection Specified Condition
      3 - 5 10 kΩ or higher
      3 - 5 Below 1 Ω (when battery voltage is applied to terminals 1 and 2)
    3. Reinstall the EFI relay.

    NG: REPLACE EFI RELAY 

    OK: Go to next step 

  9. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
    Fig 9: Identifying E9 ECM Connector Terminal
    G05264277Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
    1. Disconnect the E9 ECM connector.
    2. Measure the resistance between the wire harness side connector and body ground.

      Standard resistance 

      RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      MREL (E9-8) - Body ground Below 1 Ω
    3. Reconnect the ECM connector.

    OK: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    NG: CHECK FOR INTERMITTENT PROBLEMS 

scientia non olet · About LEMON Manuals