DTC U12AA

DTC U12AA : Lost Communication with Shifter

NOTE:

Before you troubleshoot, Review the General Troubleshooting Information .

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
U12AA Lost Communication with Shifter

DTC (A/T)

Problem verification

- 1. Turn the vehicle to the ON mode.

- 2. Clear the DTC with the HDS.

- 3. Turn the vehicle to the OFF (LOCK) mode.

- 4. Turn the vehicle to the ON mode.

- 5. Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
U12AA Lost Communication with Shifter

Is DTC U12AA indicated?

YES

The failure is duplicated. Go to step 2.

Intermittent failure, the system is OK at this time. Check for poor connections and loose terminals between the SBW shifter control module and the TCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.

Open wire check (F-CAN A_H line)

- 1. Turn the vehicle to the OFF (LOCK) mode.

- 2. Disconnect the following connectors.

SBW shifter control module 20P connector

TCM 58P connector

- 3. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	SBW shifter control module 20P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	SBW shifter control module 20P connector No. 5 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .
Test point 2	TCM 58P connector No. 34 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .

Is there continuity?

YES

The F-CAN A_H wire is OK. Go to step 3.

Repair an open in the F-CAN A_H wire between the SBW shifter control module and the TCM.

Open wire check (F-CAN A_L line)

- 1. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	SBW shifter control module 20P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	SBW shifter control module 20P connector No. 6 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .
Test point 2	TCM 58P connector No. 47 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .

Is there continuity?

YES

The F-CAN A_L wire is OK. Go to step 4.

Repair an open in the F-CAN A_L wire between the SBW shifter control module and the TCM.

Open wire check (F-CAN B_H line)

- 1. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	SBW shifter control module 20P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	SBW shifter control module 20P connector No. 9 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .
Test point 2	TCM 58P connector No. 7 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .

Is there continuity?

YES

The F-CAN B_H wire is OK. Go to step 5.

Repair an open in the F-CAN B_H wire between the SBW shifter control module and the TCM.

Open wire check (F-CAN B_L line)

- 1. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	SBW shifter control module 20P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	SBW shifter control module 20P connector No. 10 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .
Test point 2	TCM 58P connector No. 20 - Refer to: A/T Control System Connector for Inputs and Outputs (2016 2017 2018), or A/T Control System Connector for Inputs and Outputs (2019), or A/T Control System Connector for Inputs and Outputs (2020 2021) .

Is there continuity?

YES

The F-CAN B_L wire is OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or substitute a known-good TCM .

Repair an open in the F-CAN B_L wire between the SBW shifter control module and the TCM.