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Speed Signal Circuit [02/2017 - 10/2017]: Procedure

  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE) 
    1. Disconnect the combination meter assembly connector.
      GTY753236Courtesy 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 chart below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F4-6 (+S) - Body ground Ignition switch ON 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  5

    Result: 

    OK 

    See step  2

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE) 
    1. Reconnect the F4 combination meter assembly connector.
    2. Disconnect the brake actuator assembly (skid control ECU) connector.
      GTY770505Courtesy 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 chart below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A42-34 (SP1) - Body ground Ignition switch ON 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.
      GTY742839Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      1. Reconnect the A42 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 F4-5 (SI) and body ground.
      4. Turn the ignition switch ON.
      5. Turn a wheel slowly.
      6. Check the signal waveform according to the condition(s) in the chart below.
        Item Condition
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle condition Ignition switch ON 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 [02/2017 - 08/2020] 

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU). Refer to  REMOVAL [02/2017 - 09/2019] 

  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)) 
    1. Disconnect the F4 combination meter assembly connector.
    2. Disconnect the A42 brake actuator assembly (skid control ECU) connector.
    3. Measure the resistance according to the value(s) in the chart below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F4-5 (SI) - A42-34 (SP1) Always Below 1 Ω
      F4-5 (SI) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [02/2017 - 08/2020] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - EACH ECU) 
    1. Disconnect the A38 ECM connector.
    2. Disconnect the F1 certification ECU (smart key ECU assembly) connector.*1
    3. Measure the resistance according to the value(s) in the chart below.
      1. *1: w/ Smart Key System

      Standard Resistance

      Tester Connection Condition Specified Condition
      F4-6 (+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 ECM (SHORT CIRCUIT IN ECM) 
    1. Disconnect the A38 ECM connector.
    2. Reconnect the F1 certification ECU (smart key ECU assembly) connector.*1
    3. Measure the voltage according to the value(s) in the chart below.
      1. *1: w/ Smart Key System

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F4-6 (+S) - Body ground Ignition switch ON 4.5 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 [02/2017 - 10/2017] 

    Result: 

    NG 

    See step  7

  7. CONFIRM MODEL 
    1. Choose the model to be inspected.

      Result

      Result Proceed to
      w/ Smart Key System A
      w/o Smart Key System B

    Result: 

    A 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [02/2017 - ] 

    Result: 

    B 

    REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [02/2017 - 08/2020] 

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