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Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus GX 470. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK MULTI-DISPLAY 
    1. Check that waveform of the microphone using an oscilloscope.
    MULTI-DISPLAY

    Item Content
    Measurement terminal M20-2 (MIN+) - M20-3 (MIN-)
    Measurement setting 0.2 V/DIV., 0.2 μs/DIV.
    Condition w/o LEXUS Link System:
    Ignition switch ACC and steering pad switch's "Voice" switch pressed w/ LEXUS Link System:
    Ignition switch ACC and overhead junction block's "PHONE" button pressed
    Fig 1: Identifying Multi-Display
    G05266515Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Waveform that matches sound spoken into microphone is output. 

    OK: REPLACE MULTI-DISPLAY 

    NG: Go to Next Step 

  2. CHECK LEXUS LINK SYSTEM 
    1. Check if the vehicle is equipped with the LEXUS link system.

      Result 

      LEXUS LINK SYSTEM

      Result Proceed to
      w/o LEXUS Link System A
      w/ LEXUS Link System B

      B:  Go to step  6

      A: Go to Next Step 

  3. CHECK HARNESS AND CONNECTOR (OVERHEAD JUNCTION BLOCK - MULTI-DISPLAY) 
    1. Disconnect the O2 junction block connector.
    2. Disconnect the M20 display connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      OVERHEAD JUNCTION BLOCK - MULTI-DISPLAY

      Tester Connection Condition Specified Condition
      M20-4 (MACC) - O2-9 (MACC) Always Below 1 Ω
      M20-2 (MIN+) - O2-10 (MI1+) Always Below 1 Ω
      M20-3 (MIN-) - O2-12 (MIC-) Always Below 1 Ω
      M20-4 (MACC) - Body ground Always 10 kΩ or higher
      M20-2 (MIN+) - Body ground Always 10 kΩ or higher
      M20-3 (MIN-) - Body ground Always 10 kΩ or higher
      Fig 2: Identifying Harness & Connector (Overhead Junction Block - Multi-Display)
      G05266516Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

      OK: Go to Next Step 

  4. CHECK MULTI-DISPLAY (MACC VOLTAGE) 
    1. Reconnect the M20 display connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      MULTI-DISPLAY (MACC VOLTAGE)

      Tester Connection Switch Condition Specified Condition
      M20-4 (MACC) - Body ground Ignition switch ACC 4 to 6 V
      Fig 3: Identifying Multi-Display (MACC Voltage)
      G05266517Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: REPLACE MULTI-DISPLAY 

      OK: Go to Next Step 

  5. CHECK MICROPHONE ASSEMBLY 
    Fig 4: Identifying Microphone Assembly
    G04949059Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the microphone from the overhead junction block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      MICROPHONE ASSEMBLY

      Tester Connection Condition Specified Condition
      1 (MIC+) - 3 (MIC-) Always 1.9 to 2.2 kΩ

      NG: REPLACE MICROPHONE ASSEMBLY 

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

  6. CHECK HARNESS AND CONNECTOR (MAYDAY ECU - MULTI-DISPLAY AND MICROPHONE) 
    1. Disconnect the M15 ECU connector.
    2. Disconnect the M20 display connector.
    3. Disconnect the O2 microphone connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      MAYDAY ECU - MULTI-DISPLAY AND MICROPHONE

      Tester Connection Condition Specified Condition
      M15-17 (MCO+) - M20-2 (MIN+) Always Below 1 Ω
      M15-18 (MCO-) - M20-3 (MIN-) Always Below 1 Ω
      M15-7 (TACC) - O2-9 (MACC) Always Below 1 Ω
      M15-8 (MC1+) - O2-10 (MI1+) Always Below 1 Ω
      M15-9 (MC1-) - O2-12 (MIC-) Always Below 1 Ω
      M15-17 (MCO+) - Body ground Always 10 kΩ or higher
      M15-18 (MCO-) - Body ground Always 10 kΩ or higher
      M15-7 (TACC) - Body ground Always 10 kΩ or higher
      M15-8 (MC1+) - Body ground Always 10 kΩ or higher
      M15-9 (MC1-) - Body ground Always 10 kΩ or higher
      Fig 5: Identifying Harness & Connector (Mayday ECU - Multi-Display & Microphone)
      G05266519Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

      OK: Go to Next Step 

  7. CHECK MAYDAY ECU (TACC VOLTAGE) 
    1. Reconnect the M15 ECU connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      MAYDAY ECU (TACC VOLTAGE)

      Tester Connection Switch Condition Specified Condition
      M15-7 (TACC) - Body ground Ignition switch ACC 4 to 6 V
      Fig 6: Identifying MAYDAY ECU (TACC Voltage)
      G05266520Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: REPLACE MAYDAY ECU 

      OK: Go to Next Step 

  8. CHECK MICROPHONE ASSEMBLY 
    1. Remove the microphone from the overhead junction block.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      MICROPHONE ASSEMBLY

      Tester Connection Condition Specified Condition
      1 (MIC+) - 3 (MIC-) Always 1.9 to 2.2 kΩ
      Fig 7: Identifying Microphone Assembly
      G05266521Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: REPLACE MICROPHONE ASSEMBLY 

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

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