DTC U1176-87: Lost Communication with Gear Shift Control Module "A" (Powertrain Bus) Missing Message [11/2021 - ]: Procedure

1. According to the display on the GTS, select "Health Check".
2. Check for DTCs.

   Result

   Result	Proceed to
   No DTCs are output.	A
   DTCs are output.	B

3. Turn the ignition switch off.

Result: 

B 

GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [11/2021 - 03/2024]  , or Refer to  DIAGNOSTIC TROUBLE CODE CHART [03/2024 - ] 

Result: 

A 

See step  2

1. Check for DTCs.

   Powertrain > Hybrid Control > Trouble Codes 

   Result

   Result	Proceed to
   U1176-87 only is output.	A
   U0291-87 and U1176-87 are output.	B

2. Turn the ignition switch off.

Result: 

B 

TRANSMISSION FLOOR SHIFT ASSEMBLY (SHIFT CONTROL ECU) POWER SOURCE CIRCUIT FAILURE 

Result: 

A 

See step  3

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   D39-2 (BATT) - Body ground	Ignition switch off	11 to 14 V

   HINT: 

   As there might be an intermittent malfunction, inspect the following items even if the measured voltage is as specified.

   • Installation condition of fuse(s) (before removing fuse(s)) (BATT circuit)
   • Fuse condition (before and after removing fuse(s)) (BATT circuit)
   • Connection condition of connectors (BATT circuit)
   • Wire harness condition (BATT circuit)
   • Wire harness condition (GND circuit)

   Result

   Proceed to
   OK
   NG

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Transmission Floor Shift Assembly (Shift Control ECU))

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (TRANSMISSION FLOOR SHIFT ASSEMBLY (SHIFT CONTROL ECU) POWER SOURCE CIRCUIT) 

Result: 

OK 

See step  4

1. Turn the ignition switch to ON.
2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   D39-3 (IGS) - Body ground	Ignition switch ON	11 to 14 V
   D39-1 (IGP) - Body ground	Ignition switch ON	11 to 14 V

   HINT: 

   As there might be an intermittent malfunction, inspect the following items even if the measured voltage is as specified.

   • Installation condition of fuse(s) (before removing fuse(s)) (IGS, IGP circuit)
   • Fuse condition (before and after removing fuse(s)) (IGS, IGP circuit)
   • Connection condition of connectors (IGS, IGP circuit)
   • Wire harness condition (IGS, IGP circuit)
   • Wire harness condition (GND circuit)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Transmission Floor Shift Assembly (Shift Control ECU))

3. Turn the ignition switch off.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (TRANSMISSION FLOOR SHIFT ASSEMBLY (SHIFT CONTROL ECU) POWER SOURCE CIRCUIT) 

Result: 

OK 

See step  5

1. Check that the service plug grip is not installed.
   NOTE:

   After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

2. Disconnect the hybrid vehicle control ECU connector.
   NOTE:

   • Before disconnecting the connector, check that it is not loose or disconnected.
   • Check that each connector between the hybrid vehicle control ECU and transmission floor shift assembly (shift control ECU) is not loose or disconnected.
3. Disconnect the transmission floor shift assembly (shift control ECU) connectors.
   NOTE:

   • Before disconnecting the connector, check that it is not loose or disconnected.
   • Check the terminals of the connector for deformation and corrosion.
4. Disconnect the z14 battery ECU assembly connector.
5. Disconnect the B77 shift control actuator assembly (shift control actuator ECU) connector.
6. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   D67-10 (CA4H) - D39-21 (CA3H)	Ignition switch off	Below 1 Ω
   D67-23 (CA4L) - D39-6 (CA3L)	Ignition switch off	Below 1 Ω
   D39-21 (CA3H) - Body ground and other terminals	Ignition switch off	10 kΩ or higher
   D39-6 (CA3L) - Body ground and other terminals	Ignition switch off	10 kΩ or higher

   NOTE:

   Make sure that each connector between the hybrid vehicle control ECU and shift control actuator assembly (shift control actuator ECU) is not loose or disconnected and its terminals are not deformed or corroded.

   Result

   Proceed to
   OK
   NG

7. Reconnect the shift control actuator assembly (shift control actuator ECU) connector.
8. Reconnect the battery ECU assembly connector.
9. Reconnect the transmission floor shift assembly (shift control ECU) connectors.
10. Reconnect the hybrid vehicle control ECU connectors.

Result: 

OK 

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

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR