DTC : U1281, U128D (Automatic Lighting Control Unit) (2019 2020 2021)

DTC U1281  : Rain Light Sensor Unit lost communication with MICU

DTC U128D  : Rain Light Sensor Unit lost communication with gauge control module

NOTE: 

• Refer to the DTC code shown on the display, and then inspect the connectors and terminals based on the instructions in the table below.
• The DTC may be stored due to the grounding failure or the power source failure at the transmitting control unit (the grounding inspection and the power source inspection on each control unit are required prior to this checking process).
• 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 .

DTC (Automatic Lighting/Rain Sensor)

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
   U1281 Rain Light Sensor Unit lost communication with MICU
   U128D Rain Light Sensor Unit lost communication with gauge control module

   Are DTC U1281 or 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, B-CAN_L line)

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

   - 2. Disconnect the receiving control unit connector.

   Automatic lighting/rain sensor 5P connector

   - 3. Disconnect the transmitting control unit connectors.

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

   DTC	Connector
   U1281	Under-dash fuse/relay box connector M (12P)
   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	TERMINAL	TRANSMITTING CONTROL UNIT	TERMINAL
   U1281	B-CAN_H	Automatic lighting/rain sensor 5P connector - Refer to: Automatic Lighting/Rain Sensor Connector for Inputs and Outputs (2019 2020 2021)	No. 4	Under-Dash Fuse/Relay Box Connector M (12P)	No. 7
   	B-CAN_L	Automatic lighting/rain sensor 5P connector - Refer to: Automatic Lighting/Rain Sensor Connector for Inputs and Outputs (2019 2020 2021)	No. 3	Under-Dash Fuse/Relay Box Connector M (12P)	No. 1
   U128D	B-CAN_H	Automatic lighting/rain sensor 5P connector - Refer to: Automatic Lighting/Rain Sensor Connector for Inputs and Outputs (2019 2020 2021)	No. 4	Gauge control module connector A (32P) - Refer to: Gauge Control Module Connector for Inputs and Outputs (2019) or Gauge Control Module Connector for Inputs and Outputs (2020 2021) .	No. 30
   	B-CAN_L	Automatic lighting/rain sensor 5P connector - Refer to: Automatic Lighting/Rain Sensor Connector for Inputs and Outputs (2019 2020 2021)	No. 3	Gauge control module connector A (32P) - Refer to: Gauge Control Module Connector for Inputs and Outputs (2019) or Gauge Control Module Connector for Inputs and Outputs (2020 2021) .	No. 31

   Is there continuity?

   YES 

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

   DTC	Operation for transmitting control unit
   U1281	Under-Dash Fuse Relay Box
   U128D	Gauge Control Module

   NO 

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