DTC P176A-87: Lost Communication with Fail Safe Signal (Gear Shift Control Module "A") Missing Message [10/2017 - 10/2020]: Procedure

1. Disconnect the hybrid vehicle control ECU connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Hybrid Vehicle Control ECU)
   *b	Waveform (Fail-safe signal)

2. Connect an oscilloscope between the hybrid vehicle control ECU connector terminals specified in the table below.
3. Turn the power switch on (IG) and measure the waveform.

   Tester Connection	Condition	Equipment Setting
   G92-25 (SBFS) - G92-6 (E1)	Power switch on (IG)	10 V/DIV., 20 ms./DIV.

   NOTE:

   Turning the power switch on (IG) with the connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

   HINT: 

   The waveforms differ when the shift control ECU is malfunctioning.

4. Turn the power switch off.
5. Reconnect the hybrid vehicle control ECU connector.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [10/2017 - 09/2018]  , or refer to  REMOVAL [09/2018 - 10/2020] 

Result: 

NG 

See step  2

1. Disconnect the G81 shift control ECU connector.
2. Disconnect the G92 hybrid vehicle control ECU connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance (Check for Open)

   Tester Connection	Condition	Specified Condition
   G81-3 (SBFS) - G92-25 (SBFS)	Always	Below 1 Ω

   Standard Resistance (Check for Short)

   Tester Connection	Condition	Specified Condition
   G81-3 (SBFS) or G92-25 (SBFS) - Body ground and other terminals	Always	10 kΩ or higher

4. Reconnect the G92 hybrid vehicle control ECU connector.
5. Reconnect the G81 shift control ECU connector.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE SHIFT CONTROL ECU. Refer to  REMOVAL [10/2017 - 09/2018]  , or refer to  REMOVAL [09/2018 - 10/2020] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR