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Home >> Lexus >> 2021 >> LS 500h AWD >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Meter / Gauge System - Symptom Tests (2 Of 2) & Circuit Tests >> Meter / Gauge System >> Speed Signal Circuit [10/2020 - 11/2021] >> Procedure

Speed Signal Circuit [10/2020 - 11/2021]: Procedure

  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE) 
    1. Disconnect the G34*1 or G162*2 combination meter assembly connector.
      1. *1: w/o Advanced Drive
      2. *2: w/ Advanced Drive
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      W/O ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V
      W/ ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G162-8 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      HINT: 

      If any of the ECUs specified in the wiring diagram supplies power to the combination meter assembly, the combination meter assembly will output a waveform.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  2

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE) 
    1. Reconnect the G34*1 or G162*2 combination meter assembly connector.
      1. *1: w/o Advanced Drive
      2. *2: w/ Advanced Drive
    2. Disconnect the A11 skid control ECU assembly connector.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      W/O ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      A11-22 (SP1) - Body ground Power switch on (IG) 11 to 14 V
      W/ ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      A102-18 (SP1) - Body ground Power switch on (IG) 11 to 14 V

      Result

      Result Proceed to
      OK (w/o Advanced Drive) A
      OK (w/ Advanced Drive) B
      NG (w/o Advanced Drive) C
      NG (w/ Advanced Drive) D

    Result: 

    B 

    See step  4

    Result: 

    C 

    See step  5

    Result: 

    D 

    See step  6

    Result: 

    A 

    See step  3

  3. INSPECT COMBINATION METER ASSEMBLY (INPUT WAVEFORM) 
    1. Check the input waveform.
      GTY783522Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      *b Waveform
      1. Reconnect the A11 skid control ECU assembly connector.
      2. Remove the combination meter assembly with the connector(s) still connected.
      3. Connect an oscilloscope to terminal G34-20 (SI) and body ground.
      4. Turn the power switch on (IG).
      5. Turn a wheel slowly.
      6. Check the signal waveform according to the condition(s) in the table below.
        Item Condition
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle condition Power switch on (IG), wheel being rotated

        OK

        The waveform is similar to that shown in the illustration.

        HINT: 

        When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021] 

    Result: 

    NG 

    REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2020 - 10/2022] 

  4. INSPECT COMBINATION METER ASSEMBLY (INPUT WAVEFORM) 
    1. Check the input waveform.
      GTY970201Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      *b Waveform
      1. Reconnect the A102 brake actuator assembly (No. 2 skid control ECU) connector.
      2. Remove the combination meter assembly with the connector(s) still connected.
      3. Connect an oscilloscope to terminal G162-25 (SI) and body ground.
      4. Turn the power switch on (IG).
      5. Turn a wheel slowly.
      6. Check the signal waveform according to the condition(s) in the table below.
        Item Condition
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle condition Power switch on (IG), wheel being rotated

        OK

        The waveform is similar to that shown in the illustration.

        HINT: 

        When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021] 

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY (NO. 2 SKID CONTROL ECU) 

  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - SKID CONTROL ECU ASSEMBLY) 
    1. Disconnect the G34 combination meter assembly connector.
    2. Disconnect the A11 skid control ECU assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G34-20 (SI) - A11-22 (SP1) Always Below 1 Ω
      G34-20 (SI) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY (NO. 2 SKID CONTROL ECU)) 
    1. Disconnect the G162 combination meter assembly connector.
    2. Disconnect the A102 brake actuator assembly (No. 2 skid control ECU) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G162-25 (SI) - A102-18 (SP1) Always Below 1 Ω
      G162-25 (SI) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - EACH ECU) 
    1. Disconnect the G34*1 or G162*2 combination meter assembly connector.
      1. *1: w/o Advanced Drive
      2. *2: w/ Advanced Drive
    2. Disconnect the G71 certification ECU (smart key ECU assembly) connector.
    3. Disconnect the L52 stereo component amplifier assembly connector.
    4. Disconnect the G55 navigation ECU connector.
    5. Disconnect the G52 radio receiver assembly connector.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      W/O ADVANCED DRIVE

      Tester Connection Condition Specified Condition
      G34-19 (+S) - Other terminals and body ground Always 10 kΩ or higher
      W/ ADVANCED DRIVE

      Tester Connection Condition Specified Condition
      G162-8 (+S) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. INSPECT RADIO RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO RECEIVER) 
    1. Disconnect the G52 radio receiver assembly connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      W/O ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V
      W/ ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G162-8 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      HINT: 

      If the result is as specified, there may be a short circuit in the radio receiver assembly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE RADIO RECEIVER ASSEMBLY. Refer to  REMOVAL [10/2017 - 10/2022] 

    Result: 

    NG 

    See step  9

  9. INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (SHORT CIRCUIT IN STEREO COMPONENT AMPLIFIER) 
    1. Disconnect the L52 stereo component amplifier assembly connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      W/O ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      G34-19 (+S) - Body ground

      W/ ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G162-8 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      HINT: 

      If the result is as specified, there may be a short circuit in the stereo component amplifier assembly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY. Refer to  REMOVAL [10/2017 - 10/2022] 

    Result: 

    NG 

    See step  10

  10. INSPECT NAVIGATION ECU (SHORT CIRCUIT IN NAVIGATION ECU) 
    1. Disconnect the G55 navigation ECU connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      W/O ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V
      W/ ADVANCED DRIVE

      Tester Connection Switch Condition Specified Condition
      G162-8 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      HINT: 

      If the result is as specified, there may be a short circuit in the navigation ECU.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE NAVIGATION ECU. Refer to  REMOVAL [10/2017 - 10/2022] 

    Result: 

    NG 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [10/2020 - 11/2021] 

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