DTC U1281, U128D (Relay Control Module)

DTC U1281  : Relay Control Module Lost Communication With MICU (MICU Frame)

DTC U128D  : Relay Control Module Lost Communication With Gauge Control Module (VSP/NE Frame)

NOTE: 

• If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A .
• According to the detected DTC (s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the relay control module.
• Refer to the DTC shown on the display, then inspect the connectors and terminals based on the instructions.

DTC (Relay Control Module)

1. Problem verification

   -1. Clear the DTC with the HDS.

   -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 Relay control module lost communication with MICU (MICU frame)
   U128D Relay control module lost communication with gauge control module (VSP/NE frame)

   Are any DTCs indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the transmitting control units and the relay control module.

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.

   Relay control module connector A (6P)

   -3. According to the detected DTC on the following table, disconnect the transmitting control unit connector (s).

   DTC	Connector
   U1281	Body control module connector A (66P)
   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.

   Test condition

   Vehicle OFF (LOCK) mode Relay control module connector A (6P): disconnected Transmitting control unit connector (s) for indicated DTCs: disconnected

   DTC	Circuit name	Receiving control unit		Transmitting control unit
   		Connector	Terminal	Connector	Terminal
   U1281	B-CAN_H	Relay control module connector A (6P)	No. 2	Body control module connector A (66P)	No. 54
   	B-CAN_L		No. 3		No. 55
   U128D	B-CAN_H	Relay control module connector A (6P)	No. 2	Gauge control module connector A (32P)	No. 22
   	B-CAN_L		No. 3		No. 23

   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, then substitute or replace the control unit based on the instructions (see table).

   DTC	Operation for transmitting control unit
   U1281	Substitute a known-good body control module , then recheck. If DTC U1281 goes away after substitution, replace the original body control module .
   U128D	Substitute a known-good gauge control module , then recheck. If DTC U128D goes away after substitution, replace the original gauge control module .

   NO 

   Repair an open in the B-CAN_H wire and/or the B-CAN_L wire between the relay control module and the transmitting control unit.