DTC U12AA (A/T System (Without CAN Gateway)) (2016 2017 2018 2019 2020)

DTC U12AA  : Lost Communication with Shifter

DTC (A/T)

1. 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.

   NO 

   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.

2. 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
   Test point 2	TCM 58P connector No. 34

   Is there continuity?

   YES 

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

   NO 

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

3. 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
   Test point 2	TCM 58P connector No. 47

   Is there continuity?

   YES 

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

   NO 

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

4. 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
   Test point 2	TCM 58P connector No. 7

   Is there continuity?

   YES 

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

   NO 

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

5. 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
   Test point 2	TCM 58P connector No. 20

   Is there continuity?

   YES 

   The F-CAN B_L wire is OK. Update the TCM if it does not have the latest software , or substitute a known-good TCM , then recheck. If this DTC goes away and the TCM was updated, troubleshooting is complete. If this DTC goes away and the TCM was substituted, replace the original TCM .

   NO 

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