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Home >> Lexus >> 2021 >> UX 200 Base >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> (Meter / Gauge / Display) (Diagnostic Codes & Circuit Tests) >> (Meter / Gauge System) >> Speed Signal Circuit [07/2022 - ] >> Procedure

Speed Signal Circuit [07/2022 - ]: Procedure

  1. INSPECT SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) (OUTPUT WAVEFORM) 
    GTY797412Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Combination Meter Assembly)
    1. Remove the combination meter assembly with the connector(s) still connected.
    2. Check the signal waveform according to the condition(s) in the table below.
      Item Condition
      Tester connection F23-20 (SI) - Body ground
      Tool setting 5 V/DIV., 20 ms./DIV.
      Condition Ignition switch ON, 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. CHECK COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM) 
    1. Check the signal waveform according to the condition(s) in the table below.
      GTY797411Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      Item Condition
      Tester connection F23-19 (+S) - Body ground
      Tool setting 5 V/DIV., 20 ms./DIV.
      Condition Ignition switch ON, 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.
      • If the result is OK, an internal malfunction of a connected ECU can be suspected.
      • If the result is NG, an internal malfunction of the combination meter assembly can be suspected.

      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 [07/2022 - ] 

    Result: 

    A 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A48 parking brake ECU (brake actuator assembly) connector.
    2. Disconnect the F44 certification ECU (smart key ECU assembly) connector.
    3. Disconnect the F12 stereo component amplifier assembly connector.
    4. Disconnect the F1 radio receiver assembly connector.
    5. Disconnect the F23 combination meter assembly connector.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A48-27 (SPD) - F23-19 (+S) Always Below 1 Ω
      F44-19 (SPD) - F23-19 (+S) Always Below 1 Ω
      F12-17 (SPD) - F23-19 (+S) Always Below 1 Ω
      F1-27 (SPD) - F23-19 (+S) Always Below 1 Ω

      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
      A48 Parking brake ECU (brake actuator assembly)
      F1 Radio receiver assembly
      F12 Stereo component amplifier assembly
      F44 Certification ECU (smart key ECU assembly)
    2. Measure the voltage according to the value(s) in the table below.
      GTY1135355Courtesy 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 Switch Condition Specified Condition
      F23-19 (+S) - Body ground Ignition switch ON 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 parking brake ECU (brake actuator assembly), the voltage changed to the specified voltage B
      When disconnecting the connector of the radio receiver assembly, the voltage changed to the specified voltage C
      When disconnecting the connector of the stereo component amplifier assembly, the voltage changed to the specified voltage D
      When disconnecting the connector of the certification ECU (smart key ECU assembly), the voltage changed to the specified voltage E

    Result: 

    B 

    REPLACE PARKING BRAKE ECU (BRAKE ACTUATOR ASSEMBLY). Refer to  REMOVAL [07/2022 - ] 

    Result: 

    C 

    REPLACE RADIO RECEIVER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    D 

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    E 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 

    Result: 

    A 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A48 parking brake ECU (brake actuator assembly) connector.
    2. Disconnect the F44 certification ECU (smart key ECU assembly) connector.
    3. Disconnect the F12 stereo component amplifier assembly connector.
    4. Disconnect the F1 radio receiver assembly connector.
    5. Disconnect the F23 combination meter assembly connector.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A48-27 (SPD) - F23-19 (+S) Always Below 1 Ω
      F44-19 (SPD) - F23-19 (+S) Always Below 1 Ω
      F12-17 (SPD) - F23-19 (+S) Always Below 1 Ω
      F1-27 (SPD) - F23-19 (+S) Always Below 1 Ω
      A48-27 (SPD), F44-19 (SPD), F12-17 (SPD), F1-27 (SPD) or F23-19 (+S) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE) 
    1. Disconnect the skid control ECU (brake booster with master cylinder assembly) connector.
      GTY812864Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A37-11 (SP1) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY). Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - COMBINATION METER ASSEMBLY) 
    1. Disconnect the F23 combination meter assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A37-11 (SP1) or F23-20 (SI) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  8. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - COMBINATION METER ASSEMBLY) 
    1. Disconnect the F23 combination meter assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A37-11 (SP1) - F23-20 (SI) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY). Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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