DTC : U128D (Keyless Access Backup Control Unit) (2019 2020 2021)

DTC U128D  : Backup Control Unit Lost Communication with Gauge Control Module

NOTE: 

• If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to:

  Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks .

• According to the detected DTC(s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the keyless access/TPMS control unit.
• Refer to the DTC shown on the display, then inspect the connectors and terminals based on the instructions.

DTC (Backup Control Unit)

1. Problem verification

   -1. Clear the DTCs with the HDS.

   Clear DTCs

   - 2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   - 3. Wait for at least 6 seconds.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC
   U128D Backup Control Unit Lost Communication with Gauge Control Module

   Is DTC U128D indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. Open wire check (B-CAN_H line, B-CAN_L line)

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

   - 2. Disconnect the receiving control unit connector.

   Keyless access/TPMS control unit connector C (20P)

   - 3. Disconnect the transmitting control unit connector.

   Refer to the DTC shown on the display, then disconnect the connector based on the instructions (see table).

   DTC	Connector
   U128D	Gauge control module connector A (32P)

   - 4. Check for continuity between the receiving control unit and the transmitting control unit on the B-CAN_H circuit and the B-CAN_L circuit as specified in the table while in the vehicle OFF (LOCK) mode.

   DTC	CIRCUIT NAME	RECEIVING CONTROL UNIT	TRANSMITTING CONTROL UNIT
   U128D	B-CAN_H	Keyless access/TPMS control unit connector C (20P) No. 1 - Refer to: Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2019 2020 2021) .	Gauge control module connector A (32P) No. 30 - Refer to: Gauge Control Module Connector for Inputs and Outputs (2019) or Gauge Control Module Connector for Inputs and Outputs (2020 2021) .
   	B-CAN_L	Keyless access/TPMS control unit connector C (20P) No. 11 - Refer to: Keyless Access/TPMS Control Unit Connector for Inputs and Outputs (2019 2020 2021) .	Gauge control module connector A (32P) No. 31 - Refer to: Gauge Control Module Connector for Inputs and Outputs (2019) or Gauge Control Module Connector for Inputs and Outputs (2020 2021) .

   Is there continuity?

   YES 

   The B-CAN_H wire and the B-CAN_L wire are OK. According to the detected DTC on the following table replace the correspond control unit.

   DTC	Operation for transmitting control unit
   U128D	Gauge control module

   NO 

   Repair an open in the B-CAN_H wire and/or the B-CAN_L wire.