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Home >> Lexus >> 2021 >> GX 460 Base >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Meter / Gauge / Display System (Diagnostic Codes & Symptom Tests) >> Meter / Gauge System >> Speed Signal Circuit [08/2019 - 08/2021] >> Procedure

Speed Signal Circuit [08/2019 - 08/2021]: Procedure

  1. CHECK ECU TERMINAL VOLTAGE (INPUT VOLTAGE) 
    1. Disconnect the combination meter assembly connector.
      GTY958860Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G3-17 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  2

  2. CHECK COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE) 
    1. Disconnect the master cylinder solenoid (skid control ECU) connector.
      GTY958945Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Master Cylinder Solenoid [Skid Control ECU])
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A7-12 (SP1) - Body ground Engine switch on (IG) 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  4

    Result: 

    OK 

    See step  3

  3. CHECK COMBINATION METER ASSEMBLY (SPEED SIGNAL) 
    1. Check the input waveform.
      GTY958908Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      *b Waveform
      1. Reconnect the combination meter assembly connector.
      2. Remove the combination meter assembly with the connector(s) still connected.
      3. Connect an oscilloscope to terminal G3-18 (SI) and body ground.
      4. Turn the engine switch on (IG).
      5. Check the signal waveform according to the condition(s) in the table below.

        Measurement Condition

        Item Condition
        Tester Connection G3-18 (SI) - Body ground
        Tool setting 5 V/DIV., 20 ms./DIV.
        Condition Driving at approximately 20 km/h (12 mph)

        OK

        The waveform displayed is as 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 [08/2019 - ] 

    Result: 

    NG 

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU). Refer to  DISASSEMBLY [08/2015 - ] 

  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - SKID CONTROL ECU) 
    1. Disconnect the G3 combination meter assembly connector.
    2. Disconnect the A7 master cylinder solenoid (skid control ECU) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G3-18 (SI) - A7-12 (SP1) Always Below 1 Ω
      A7-12 (SP1) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [08/2019 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  5. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. *1: for 17 Speakers
    2. *2: for 9 Speakers
    3. *3: w/ Rain Sensor
    4. *4: w/o Navigation System
    5. *5: w/ Navigation System
    1. Disconnect the combination meter assembly connector.
      GTY958861Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Disconnect the G44 ECM connector.
    3. Disconnect the G118 windshield wiper relay assembly connector.*3
    4. Disconnect the R31*1 or H21*2 stereo component amplifier assembly connector.*5
    5. Disconnect the H3*4 or H11*5 multi-media module receiver assembly connector.
    6. Disconnect the H22 stereo component amplifier assembly connector.*4
    7. Disconnect the G113 certification ECU (smart key ECU assembly) connector.
    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      G3-17 (+S) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. CHECK STEREO COMPONENT AMPLIFIER ASSEMBLY 
    1. *1: for 17 Speakers
    2. *2: for 9 Speakers
    3. *3: w/ Navigation System
    4. *4: w/o Navigation System
    1. Disconnect the combination meter assembly connector.
      GTY958861Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Disconnect the R31*1 or H21*2 stereo component amplifier assembly connector.*3
    3. Disconnect the H22 stereo component amplifier assembly connector.*4
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G3-17 (+S) - Body ground Engine switch on (IG) 11 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 

    for 17 Speakers:

    Refer to REMOVAL [08/2016 - 08/2021]

    for 9 Speakers:

    Refer to REMOVAL [08/2015 - 08/2021]

    Result: 

    NG 

    See step  7

  7. CHECK VEHICLE TYPE 
    1. Check vehicle condition.

      Result

      Result  Proceed to 
      w/ Rain Sensor A
      w/o Rain Sensor B

    Result: 

    B 

    See step  9

    Result: 

    A 

    See step  8

  8. CHECK WINDSHIELD WIPER RELAY ASSEMBLY 
    1. Disconnect the combination meter assembly connector.
      GTY958861Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Disconnect the G118 windshield wiper relay assembly connector.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G3-17 (+S) - Body ground Engine switch on (IG) 11 to 14 V

      HINT: 

      If the result is as specified, there may be a short circuit in the windshield wiper relay assembly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE WINDSHIELD WIPER RELAY ASSEMBLY. Refer to  REMOVAL [08/2019 - ] 

    Result: 

    NG 

    See step  9

  9. CHECK MULTI-MEDIA MODULE RECEIVER ASSEMBLY 
    1. Disconnect the combination meter assembly connector.
      GTY958861Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Disconnect the H3*1 or H11*2 multi-media module receiver assembly connector.
      1. *1: w/o Navigation System
      2. *2: w/ Navigation System
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G3-17 (+S) - Body ground Engine switch on (IG) 11 to 14 V

      HINT: 

      If the result is as specified, there may be a short circuit in the multi-media module receiver assembly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE MULTI-MEDIA MODULE RECEIVER ASSEMBLY. Refer to  REMOVAL [08/2015 - 08/2021] 

    Result: 

    NG 

    See step  10

  10. CHECK ECM 
    1. Disconnect the combination meter assembly connector.
      GTY958861Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Disconnect the G44 ECM connector.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G3-17 (+S) - Body ground Engine switch on (IG) 11 to 14 V

      HINT: 

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

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [08/2015 - ] 

    Result: 

    NG 

    See step  11

  11. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 
    1. Disconnect the combination meter assembly connector.
      GTY958861Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Combination Meter Assembly)
    2. Disconnect the G113 certification ECU (smart key ECU assembly) connector.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      G3-17 (+S) - Body ground Engine switch on (IG) 11 to 14 V

      HINT: 

      If the result is as specified, there may be a short circuit in the certification ECU (smart key ECU assembly).

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [08/2019 - 08/2021] 

    Result: 

    NG 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [08/2019 - ] 

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