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Home >> Lexus >> 2017 >> IS 350 Base, 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 [10/2017 - 09/2020] >> Procedure

Speed Signal Circuit [10/2017 - 09/2020]: Procedure

  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE) 
    GTY461249Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Combination Meter Assembly)
    1. Disconnect the K3 combination meter assembly connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine 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

      Result Proceed to
      OK A
      NG (w/ Navigation System) B
      NG (w/ Audio and Visual System) C

    Result: 

    B 

    See step  5

    Result: 

    C 

    See step  8

    Result: 

    A 

    See step  2

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE) 
    1. Reconnect the K3 combination meter assembly connector.
    2. Disconnect the A105 brake actuator assembly (skid control ECU) connector.
      GTY794946Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Brake Actuator Assembly (Skid Control ECU))
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A105-14 (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. INSPECT BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) (INPUT WAVEFORM) 
    1. Check the input waveform.
      GTY470703Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      1. Reconnect the A105 brake actuator assembly (skid control ECU) connector.
      2. Remove the combination meter assembly with the connector(s) still connected.
      3. Connect an oscilloscope to terminal K3-20 (SI) and body ground.
      4. Turn the engine 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 Engine 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 [10/2016 - 09/2020] 

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU). Refer to  REMOVAL [10/2016 - 09/2020] 

  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)) 
    1. Disconnect the K3 combination meter assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      K3-20 (SI) - A105-14 (SP1) Always Below 1 Ω
      K3-20 (SI) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [10/2016 - 09/2020] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  5. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A106*1 or A91*2 ECM connector.
    2. Disconnect the K6 certification ECU (smart key ECU assembly) connector.
    3. Disconnect the K58 radio receiver assembly connector.
    4. Disconnect the P23 stereo component amplifier assembly connector.
    5. Disconnect the K66 DCM (telematics transceiver) connector*3.
      1. *1: for 2GR-FKS
      2. *2: for 8AR-FTS
      3. *3: w/ Manual (SOS) Switch
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      K3-19 (+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. INSPECT RADIO RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO RECEIVER ASSEMBLY) 
    1. Connect the A106*1 or A91*2 ECM connector.
    2. Connect the K6 certification ECU (smart key ECU assembly) connector.
    3. Connect the P23 stereo component amplifier assembly connector.
    4. Connect the K66 DCM (telematics transceiver) connector*3.
      1. *1: for 2GR-FKS
      2. *2: for 8AR-FTS
      3. *3: w/ Manual (SOS) Switch
    5. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine 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 [04/2013 - 09/2020] 

    Result: 

    NG 

    See step  7

  7. INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (SHORT CIRCUIT IN STEREO COMPONENT AMPLIFIER ASSEMBLY) 
    1. Disconnect the P23 stereo component amplifier assembly connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine 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 [08/2015 - 09/2020] 

    Result: 

    NG 

    See step  11

  8. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A106*1 or A91*2 ECM connector.
    2. Disconnect the K6 certification ECU (smart key ECU assembly) connector.
    3. Disconnect the K72 radio receiver assembly connector.
    4. Disconnect the P24 stereo component amplifier assembly connector.
    5. Disconnect the K66 DCM (telematics transceiver) connector*3.
      1. *1: for 2GR-FKS
      2. *2: for 8AR-FTS
      3. *3: w/ Manual (SOS) Switch
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      K3-19 (+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  9

  9. INSPECT RADIO RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO RECEIVER ASSEMBLY) 
    1. Connect the A106*1 or A91*2 ECM connector.
    2. Connect the K6 certification ECU (smart key ECU assembly) connector.
    3. Connect the P24 stereo component amplifier assembly connector.
    4. Connect the K66 DCM (telematics transceiver) connector*3.
      1. *1: for 2GR-FKS
      2. *2: for 8AR-FTS
      3. *3: w/ Manual (SOS) Switch
    5. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine 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 [04/2013 - 09/2020] 

    Result: 

    NG 

    See step  10

  10. INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (SHORT CIRCUIT IN STEREO COMPONENT AMPLIFIER ASSEMBLY) 
    1. Disconnect the P24 stereo component amplifier assembly connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine 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 [08/2015 - 09/2020] 

    Result: 

    NG 

    See step  11

  11. INSPECT ECM (SHORT CIRCUIT IN ECM) 
    1. Disconnect the A106*1 or A91*2 ECM connector.
      1. *1: for 2GR-FKS
      2. *2: for 8AR-FTS
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      HINT: 

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

      Result

      Result Proceed to
      OK A
      NG (w/ Manual (SOS) Switch) B
      NG (w/o Manual (SOS) Switch) C

    Result: 

    A 

    REPLACE ECM 

    for 2GR-FKS: Refer to REMOVAL [10/2017 - ]

    for 8AR-FTS: Refer to REMOVAL [08/2015 - ]

    Result: 

    C 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [08/2015 - 09/2020] 

    Result: 

    B 

    See step  12

  12. INSPECT DCM (TELEMATICS TRANSCEIVER) (SHORT CIRCUIT IN DCM (TELEMATICS TRANSCEIVER)) 
    1. Disconnect the K66 DCM (telematics transceiver) connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      HINT: 

      If the result is as specified, there may be a short circuit in the DCM (telematics transceiver).

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE DCM (TELEMATICS TRANSCEIVER). Refer to  REMOVAL [10/2017 - 09/2020] 

    Result: 

    NG 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [08/2015 - 09/2020] 

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