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

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

Pre-procedure1

1. 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)

   Procedure1

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

   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

3. 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

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

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 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

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