LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2005 >> LX 470 >> Repair and Diagnosis >> Engine Performance >> System >> Engine - Diagnostics >> Circuit Inspection >> ECM Power Source Circuit >> Inspection Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Inspection Procedure

  1. Check voltage between terminals +B and E1 of ECM connectors. 

    PREPARATION: 

    Turn the ignition switch ON.

    CHECK: 

    Measure the voltage between terminals +B and E1 of the ECM connectors.

    OK: 

    1. Voltage: 9 to 14 V 
    Fig 1: Identifying Terminals +B And E1 Of ECM Connectors
    G02985494Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. OK : Proceed to next circuit inspection shown on problem symptoms table (See  PROBLEM SYMPTOMS TABLE  ). 
    2. NG : Go to Next Step. 
  2. Check for open in harness and connector between terminal E1 of ECM and body ground (See  PROCEDURE  ). 
    1. NG : Repair or replace harness or connector. 
    2. OK : Go to Next Step. 
  3. Check voltage between terminal IGSW of ECM connector and body ground. 

    PREPARATION: 

    Turn the ignition switch ON.

    CHECK: 

    Measure the voltage between terminal IGSW of the ECM connector and body ground.

    OK: 

    1. Voltage: 9 to 14 V 
    Fig 2: Identifying Terminal IGSW Of ECM Connector And Body Ground
    G02985495Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. OK : Go to step   6 . 
    2. NG : Go to Next Step. 
  4. Check IGN fuse. 

    PREPARATION: 

    Remove the IGN fuse from the cowl side J/B RH.

    CHECK: 

    Check the continuity of the IGN fuse.

    OK: 

    1. Continuity 
    Fig 3: Removing IGN Fuse From Cowl Side J/B RH
    G02985496Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG : Check for short in all harness and components connected to IGN fuse. 
    2. OK : Go to Next Step. 
  5. Check ignition switch (See  INSPECTION  ). 
    1. NG : Replace ignition switch. 
    2. OK : Check and repair harness and connector between battery and ignition switch, and ignition switch and ECM (See  PROCEDURE  ). 
  6. Check voltage between terminal MREL of ECM connector and body ground. 

    PREPARATION: 

    Turn the ignition switch ON.

    CHECK: 

    Measure the voltage between terminal MREL of the ECM connector and body ground.

    OK: 

    1. Voltage: 9 to 14 V 
    Fig 4: Identifying Terminal MREL Of ECM Connector And Body Ground
    G02985497Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG : Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ). 
    2. OK : Go to Next Step. 
  7. Check EFI or ECD No. 1 fuse of engine room J/B. 

    PREPARATION: 

    Remove the EFI or ECD No. 1 fuse from the engine room J/B.

    CHECK: 

    Check continuity of EFI or ECD No. 1 fuse.

    OK: 

    1. Continuity 
    Fig 5: Removing EFI Or ECD No. 1 Fuse From Engine Room J/B
    G02985498Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG : Check for short in all harness and components connected to EFI or ECD No. 1 fuse. 
    2. OK : Go to Next Step. 
  8. Check EFI or ECD relay (See  EFI MAIN RELAY  ). 
    1. NG : Replace EFI or ECD relay. 
    2. OK : Go to Next Step. 
  9. Check for open and short in harness and connector between terminal MREL of ECM and body ground (See  PROCEDURE  ). 
    1. NG : Repair or replace harness or connector. 
    2. OK : Check and repair harness or connector between EFI or ECD No. 1 fuse and battery (See  PROCEDURE  ).