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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 [09/2020 - 11/2021] >> Procedure

Speed Signal Circuit [09/2020 - 11/2021]: Procedure

  1. INSPECT COMBINATION METER ASSEMBLY (INPUT WAVEFORM) 
    GTY971742Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Combination Meter Assembly)
    *b Input Waveform
    1. Check the signal waveform according to the condition(s) in the table below.
      Item Condition
      Tester connection K3-20 (SI) - Body ground
      Tool setting 5 V/DIV., 20 ms./DIV.
      Condition Engine switch on (IG), wheel being rotated
      NOTE:

      Perform the inspection from the back of the connector with the connector connected.

      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

      Result  Proceed to
      The measured waveform is similar to that in the illustration A
      The measured waveform is not similar to that in the illustration
      (Stuck low)      		 B
      The measured waveform is not similar to that in the illustration
      (Stuck high)      		 C

    Result: 

    B 

    See step  6

    Result: 

    C 

    See step  8

    Result: 

    A 

    See step  2

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM) 
    GTY970692Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Combination Meter Assembly)
    *b Output Waveform
    1. Check the signal waveform according to the condition(s) in the table below.
      Item Condition
      Tester connection K3-19 (+S) - Body ground
      Tool setting 5 V/DIV., 20 ms./DIV.
      Condition Engine switch on (IG), wheel being rotated
      NOTE:

      Perform the inspection from the back of the connector with the connector connected.

      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.
      • The waveform (B) changes depending on the connected ECUs.

      Result

      Result  Proceed to
      The measured waveform is similar to that in the illustration A
      The measured waveform is not similar to that in the illustration
      (Stuck low)      		 B
      The measured waveform is not similar to that in the illustration
      (Stuck high)      		 C

    Result: 

    B 

    See step  4

    Result: 

    C 

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

    Result: 

    A 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A91*1 or A106*2 ECM connector.
    2. Disconnect the K6 certification ECU (smart key ECU assembly) connector.
    3. Disconnect the K172 radio receiver assembly connector.
    4. Disconnect the K176 navigation ECU connector.*3
    5. Disconnect the P23*3 or P44*4 stereo component amplifier assembly connector.
    6. Disconnect the K3 combination meter assembly connector.
    7. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A91-44 (SPD) - K3-19 (+S)*1 Always Below 1 Ω
      A106-39 (SPD) - K3-19 (+S)*2 Always Below 1 Ω
      K6-5 (SPD) - K3-19 (+S) Always Below 1 Ω
      K172-27 (SPD) - K3-19 (+S) Always Below 1 Ω
      K176-9 (SPD) - K3-19 (+S)*3 Always Below 1 Ω
      P23-17 (SPD) - K3-19 (+S)*3 Always Below 1 Ω
      P44-11 (SPD) - K3-19 (+S)*4 Always Below 1 Ω
      1. *1: for 8AR-FTS
      2. *2: for 2GR-FKS
      3. *3: w/ Navigation System
      4. *4: w/o Navigation System

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    CHECK THE VOLTAGE AT TERMINAL SPD OF EACH ECU 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  4. INSPECT EACH ECU (INTERNAL SHORT) 
    1. Disconnect one of the connectors below.
      NOTE:

      After disconnecting a connector, perform all steps with all other devices connected.

      Connector ECU
      A91*1 ECM
      A106*2
      K6 Certification ECU (smart key ECU assembly)
      K172 Radio receiver assembly
      K176*3 Navigation ECU
      P23*3 Stereo component amplifier assembly
      P44*4
      1. *1: for 8AR-FTS
      2. *2: for 2GR-FKS
      3. *3: w/ Navigation System
      4. *4: w/o Navigation System
    2. Measure the voltage according to the value(s) in the table below.
      GTY971843Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      NOTE:
      • Make sure to perform this inspection with the wheels stopped.
      • Perform the inspection from the back of the connector with the connector connected.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K3-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V
    3. Repeat steps (a) and (b) for each connected ECU.

      HINT: 

      If the waveform changes to the waveform shown in the illustration after disconnecting a connector, an internal short in the disconnected ECU is suspected.

      Result

      Result  Proceed to
      After performing the inspection procedure for all connectors, the voltage did not change to the specified voltage A
      When disconnecting the connector of the ECM, the voltage changed to the specified voltage B
      When disconnecting the connector of the certification ECU (smart key ECU assembly), the voltage changed to the specified voltage C
      When disconnecting the connector of the radio receiver assembly, the voltage changed to the specified voltage D
      When disconnecting the connector of the navigation ECU, the voltage changed to the specified voltage
      (w/ Navigation System)      		 E
      When disconnecting the connector of the stereo component amplifier assembly, the voltage changed to the specified voltage F

    Result: 

    B 

    REPLACE ECM 

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

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

    Result: 

    C 

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

    Result: 

    D 

    REPLACE RADIO RECEIVER ASSEMBLY. Refer to  REMOVAL [09/2020 - ] 

    Result: 

    E 

    REPLACE NAVIGATION ECU. Refer to  REMOVAL [09/2020 - ] 

    Result: 

    F 

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY. Refer to  REMOVAL [09/2020 - ] 

    Result: 

    A 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A91*1 or A106*2 ECM connector.
    2. Disconnect the K6 certification ECU (smart key ECU assembly) connector.
    3. Disconnect the K172 radio receiver assembly connector.
    4. Disconnect the K176 navigation ECU connector.*3
    5. Disconnect the P23*3 or P44*4 stereo component amplifier assembly connector.
    6. Disconnect the K3 combination meter assembly connector.
    7. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A91-44 (SPD)*1, A106-39 (SPD)*2, K6-5 (SPD), K172-27 (SPD), K176-9 (SPD)*3, P23-17 (SPD)*3 or P44-11 (SPD)*4 - K3-19 (+S) Always Below 1 Ω
      A91-44 (SPD)*1, A106-39 (SPD)*2, K6-5 (SPD), K172-27 (SPD), K176-9 (SPD)*3, P23-17 (SPD)*3, P44-11 (SPD)*4 or K3-19 (+S) - Body ground Always 10 kΩ or higher
      1. *1: for 8AR-FTS
      2. *2: for 2GR-FKS
      3. *3: w/ Navigation System
      4. *4: w/o Navigation System

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE) 
    1. Disconnect the A111 skid control ECU (brake actuator assembly) connector.
      GTY971051Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Skid Control ECU (Brake Actuator Assembly))
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A111-18 (SP1) - Body ground Engine switch on (IG) 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY). Refer to  REMOVAL [09/2020 - 11/2021] 

    Result: 

    NG 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - COMBINATION METER ASSEMBLY) 
    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
      A111-18 (SP1) or K3-20 (SI) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  8. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A111 skid control ECU (brake actuator assembly) connector.
    2. Disconnect the K3 combination meter assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A111-18 (SP1) - K3-20 (SI) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY). Refer to  REMOVAL [09/2020 - 11/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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