DTC P177A-87: Lost Communication with Gear Shift Control Module Backup Power Supply Missing Message [10/2022 - 08/2023]: Procedure

Pre-procedure1

• Disconnect the C35 transmission floor shift assembly (shift control ECU) connector.
• Disconnect the H116 integration control supply (integrated capacitor) connector.

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

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  C35-17 (BUBI) - H116-3 (RO)	Always	Below 1 Ω	Ω
  C35-17 (BUBI) or H116-3 (RO) - Body ground and other terminals	Always	10 kΩ or higher	kΩ

  Result

  Proceed to
  OK
  NG

Post-procedure1

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

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  2

Pre-procedure1

• Connect an oscilloscope between the transmission floor shift assembly (shift control ECU) terminals specified in the table below.

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

  *a	Component with harness connected (Transmission Floor Shift Assembly (Shift Control ECU))
  *b	Waveform (Integrated capacitor condition signal)

• Turn the ignition switch to ON and measure the waveform.

  Tester Connection	Condition	Equipment Setting
  C35-17 (BUBI) - C35-9 (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

• Turn the ignition switch off.

Result: 

OK 

REPLACE TRANSMISSION FLOOR SHIFT ASSEMBLY (SHIFT CONTROL ECU). Refer to  REMOVAL [10/2022 - ] 

Result: 

NG 

See step  3

Pre-procedure1

• Disconnect the H116 integration control supply (integrated capacitor) connector.

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

  Standard Voltage

  Tester Connection	Condition	Specified Condition	Result
  H116-7 (+B) - Body ground	Always	11 to 14 V	V

  Result

  Proceed to
  OK
  NG

Post-procedure1

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

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

Pre-procedure1

• Disconnect the H116 integration control supply (integrated capacitor) connector.
• Turn the ignition switch to ON.

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

  Standard Voltage

  Tester Connection	Condition	Specified Condition	Result
  H116-16 (IG) - Body ground	Ignition switch ON	11 to 14 V	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

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

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

Pre-procedure1

• Disconnect the C35 transmission floor shift assembly (shift control ECU) connector.
• Disconnect the H116 integration control supply (integrated capacitor) connector.

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

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  C35-13 (BUB) - H116-1 (BUSE)	Always	Below 1 Ω	Ω
  C35-13 (BUB) or H116-1 (BUSE) - Body ground and other terminals	Always	10 kΩ or higher	kΩ

  Result

  Proceed to
  OK
  NG

Post-procedure1

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

Result: 

OK 

REPLACE INTEGRATION CONTROL SUPPLY (INTEGRATED CAPACITOR). Refer to  REMOVAL [10/2022 - 08/2023] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR