2013 Lexus LS 460L AWDFACTORY OEM SERVICE PROCEDURE

DTC B1579: Voice Recognition Microphone Disconnected: Procedure

  1. CONFIRM MODEL 
    1. Choose the model to be inspected.
      MODEL

      Model Proceed to
      w/o Manual (SOS) Switch A
      w/ Manual (SOS) Switch B

    B → See step   7 

    A: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (MULTI-MEDIA MODULE RECEIVER ASSEMBLY - MAP LIGHT ASSEMBLY) 
    1. Disconnect the L146 multi-media module receiver assembly connector.
    2. Disconnect the X4 map light assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L146-27 (MIN+) - X4-21 (MI1+) Always Below 1 Ω
      L146-29 (MACC) - X4-22 (ACC) Always Below 1 Ω
      L146-48 (MIN-) - X4-20 (MIC-) Always Below 1 Ω
      L146-49 (SNS2) - X4-31 (SIN2) Always Below 1 Ω
      L146-27 (MIN+) - Body ground Always 10 kΩ or higher
      L146-28 (SGND) - Body ground Always 10 kΩ or higher
      L146-29 (MACC) - Body ground Always 10 kΩ or higher
      L146-48 (MIN-) - Body ground Always 10 kΩ or higher
      L146-49 (SNS2) - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. CHECK MULTI-MEDIA MODULE RECEIVER ASSEMBLY 
    1. Measure the voltage according to the value(s) in the table below.
      GTY401254Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      L146-29 (MACC) - Body ground Engine switch on (ACC) 4 to 6 V
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L146-28 (SGND) - Body ground Always Below 1 Ω
      L146-48 (MIN-) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Component with harness connected
      (Multi-media Module Receiver Assembly)

    NG → See step   15 

    OK: Go to next step 

  4. INSPECT MAP LIGHT ASSEMBLY 
    1. Remove the map light assembly. Refer to REMOVAL [09/2012 - ] .
      GTY409040Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      20 (MIC-) - 31 (SIN2) Always Below 1 Ω

    NG → See step   6 

    OK: Go to next step 

  5. CHECK MAP LIGHT ASSEMBLY 
    1. Turn the engine switch on (ACC).
      GTY409868Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect an oscilloscope to terminals X4-20 (MIC-) and X4-21 (MI1+) of the map light assembly connector.
    3. Check the waveform of the telephone microphone assembly using the oscilloscope.
      TEXT IN ILLUSTRATION

      *a Component with harness connected
      (Map Light Assembly)
      RESULT

      Result Proceed to
      A waveform synchronized with the voice input to the map light assembly is output. A
      A waveform synchronized with the voice input to the map light assembly is not output. B

    B → See step   6 

    A → See step   15 

  6. CHECK TELEPHONE MICROPHONE ASSEMBLY 
    1. Replace the telephone microphone assembly with a new or normally functioning one. Refer to REMOVAL [09/2012 - ] .
    2. Check if the same DTC is output again.
      RESULT

      Result Proceed to
      No DTCs are output. A
      DTCs are output. B

    B → See step   16 

    A → END (TELEPHONE MICROPHONE ASSEMBLY IS DEFECTIVE) 

  7. CHECK HARNESS AND CONNECTOR (MULTI-MEDIA MODULE RECEIVER ASSEMBLY - MAP LIGHT ASSEMBLY) 
    1. Disconnect the L146 multi-media module receiver assembly connector.
    2. Disconnect the X4 map light assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L146-49 (SNS2) - X4-31 (SIN2) Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  8. CHECK HARNESS AND CONNECTOR (MULTI-MEDIA MODULE RECEIVER ASSEMBLY - DCM [TELEMATICS TRANSCEIVER]) 
    1. Disconnect the L146 multi-media module receiver assembly connector.
    2. Disconnect the L111 DCM (telematics transceiver) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L146-27 (MIN+) - L111-18 (MCO+) Always Below 1 Ω
      L146-48 (MIN-) - L111-19 (MCO-) Always Below 1 Ω
      L146-27 (MIN+) - Body ground Always 10 kΩ or higher
      L146-48 (MIN-) - Body ground Always 10 kΩ or higher
      L146-28 (SGND) - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  9. CHECK HARNESS AND CONNECTOR (DCM [TELEMATICS TRANSCEIVER] - MAP LIGHT ASSEMBLY) 
    1. Disconnect the L111 DCM (telematics transceiver) connector.
    2. Disconnect the X4 map light assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L111-33 (MCVD) - X4-22 (ACC) Always Below 1 Ω
      L111-34 (MCI+) - X4-21 (MI1+) Always Below 1 Ω
      L111-35 (MCI-) - X4-20 (MIC-) Always Below 1 Ω
      L111-33 (MCVD) - Body ground Always 10 kΩ or higher
      L111-34 (MCI+) - Body ground Always 10 kΩ or higher
      L111-35 (MCI-) - Body ground Always 10 kΩ or higher
      L111-32 (SGND) - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  10. CHECK MULTI-MEDIA MODULE RECEIVER ASSEMBLY 
    1. Disconnect the L111 DCM (telematics transceiver) connector.
      GTY401679Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L146-28 (SGND) - Body ground Always Below 1 Ω
      L146-48 (MIN-) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Component with harness connected
      (Multi-media Module Receiver Assembly)

    NG → See step   15 

    OK: Go to next step 

  11. CHECK DCM (TELEMATICS TRANSCEIVER) 
    1. Measure the voltage according to the value(s) in the table below.
      GTY401873Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      L111-33 (MCVD) - Body ground Engine switch on (ACC) 4 to 6 V
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L111-32 (SGND) - Body ground Always Below 1 Ω
      L111-35 (MCI-) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Component with harness connected
      (DCM [Telematics Transceiver])

    NG → See step   17 

    OK: Go to next step 

  12. INSPECT MAP LIGHT ASSEMBLY 
    1. Remove the map light assembly. Refer to REMOVAL [09/2012 - ] .
      GTY409040Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      20 (MIC-) - 31 (SIN2) Always Below 1 Ω

    NG → See step   14 

    OK: Go to next step 

  13. CHECK MAP LIGHT ASSEMBLY 
    1. Turn the engine switch on (ACC).
      GTY409868Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect an oscilloscope to terminals X4-21 (MI1+) and X4-20 (MIC-) of the map light assembly connector.
    3. Check the waveform of the telephone microphone assembly using the oscilloscope.
      TEXT IN ILLUSTRATION

      *a Component with harness connected
      (Map Light Assembly)
      RESULT

      Result Proceed to
      A waveform synchronized with the voice input to the map light assembly is output. A
      A waveform synchronized with the voice input to the map light assembly is not output. B

    B → See step   14 

    A → See step   15 

  14. CHECK TELEPHONE MICROPHONE ASSEMBLY 
    1. Replace the telephone microphone assembly with a new or normally functioning one. Refer to REMOVAL [09/2012 - ] .
    2. Check if the same DTC is output again.
      RESULT

      Result Proceed to
      No DTCs are output. A
      DTCs are output. B

    B → See step   16 

    A → END (TELEPHONE MICROPHONE ASSEMBLY IS DEFECTIVE) 

  15. REPLACE MULTI-MEDIA MODULE RECEIVER ASSEMBLY. Refer to  REMOVAL [09/2012 - ] 
  16. REPLACE MAP LIGHT ASSEMBLY. Refer to  REMOVAL [09/2012 - ] 
  17. REPLACE DCM (TELEMATICS TRANSCEIVER). Refer to  REMOVAL [09/2012 - ] 
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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