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DTC P177A-87: Lost Communication with Gear Shift Control Module Backup Power Supply Missing Message [11/2021 - ]: Procedure

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  1. CHECK HARNESS AND CONNECTOR (SHIFT CONTROL ECU - INTEGRATED CAPACITOR) 

    Pre-procedure1

    1. Disconnect the D39 transmission floor shift assembly (shift control ECU) connector.
    2. Disconnect the G102 integration control supply (integrated capacitor) connector.

      Procedure1

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D39-17 (BUBI) - G102-3 (RO) Always Below 1 Ω
      D39-17 (BUBI) or G102-3 (RO) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. Connect the integration control supply (integrated capacitor) connector.
    5. Connect the transmission floor shift assembly (shift control ECU) connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. INSPECT TRANSMISSION FLOOR SHIFT ASSEMBLY (SHIFT CONTROL ECU) (CHECK BUBI TERMINAL WAVEFORM) 

    Pre-procedure1

    1. Connect an oscilloscope between the transmission floor shift assembly (shift control ECU) terminals specified in the table below.
    2. Turn the ignition switch to ON.

      Procedure1

    3. Measure the waveform.
      GTY1065235Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Transmission Floor Shift Assembly (Shift Control ECU))
      *b Waveform (Integrated capacitor condition signal)
      Tester Connection Condition Equipment Setting
      D39-17 (BUBI) - D39-9 (E1) Ignition switch ON 10 V/DIV., 10 ms./DIV.

      HINT: 

      The duty ratio changes according to the vehicle condition.

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. Turn the ignition switch off.

    Result: 

    OK 

    REPLACE TRANSMISSION FLOOR SHIFT ASSEMBLY (SHIFT CONTROL ECU). Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    See step  3

  3. INSPECT INTEGRATION CONTROL SUPPLY (INTEGRATED CAPACITOR) (+B TERMINAL VOLTAGE) 

    Pre-procedure1

    1. Disconnect the G102 integration control supply (integrated capacitor) connector.

      Procedure1

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      G102-7 (+B) - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    3. Connect the integration control supply (integrated capacitor) connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. INSPECT INTEGRATION CONTROL SUPPLY (INTEGRATED CAPACITOR) (IG TERMINAL VOLTAGE) 

    Pre-procedure1

    1. Disconnect the G102 integration control supply (integrated capacitor) connector.
    2. Turn the ignition switch to ON.

      Procedure1

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      G102-16 (IG) - Body ground Ignition switch to ON 11 to 14 V

      Result

      Proceed to
      OK
      NG
      NOTE:

      Turning the ignition switch to ON with the connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

      Post-procedure1

    4. Turn the ignition switch off.
    5. Connect the integration control supply (integrated capacitor) connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (SHIFT CONTROL ECU - INTEGRATED CAPACITOR) 

    Pre-procedure1

    1. Disconnect the D39 transmission floor shift assembly (shift control ECU) connector.
    2. Disconnect the G102 integration control supply (integrated capacitor) connector.

      Procedure1

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D39-13 (BUB) - G102-1 (BUSE) Always Below 1 Ω
      D39-13 (BUB) or G102-1 (BUSE) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. Connect the integration control supply (integrated capacitor) connector.
    5. Connect the transmission floor shift assembly (shift control ECU) connector.

    Result: 

    OK 

    REPLACE INTEGRATION CONTROL SUPPLY (INTEGRATED CAPACITOR). Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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