DTC U128D (Body Control Module)

DTC U128D  : BCM (Body Control Module) 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 .
• According to the detected DTC (s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the body control module.
• Refer to the DTC shown on the display, then inspect the connectors and terminals based on the instructions.

DTC (Body Control Module)

1. Problem verification

   -1. Turn the vehicle to the ON mode.

   -2. Clear the DTCs with the HDS.

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

   -4. Wait for at least 6 seconds.

   -5. Check for DTCs with the HDS.

   DTC Description	DTC
   U128D BCM (Body Control Module) 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.

   Body control module connector B (36P)

   -3. Disconnect the transmitting control unit connector (s).

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

   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.

   Test condition

   Vehicle OFF (LOCK) mode Body control module connector B (36P): disconnected Transmitting control unit connector (s) for indicated DTCs: disconnected

   DTC	Circuit name	Receiving control unit		Transmitting control unit
   		Connector	Terminal	Connector	Terminal
   U128D	B-CAN H	Body control module connector B (36P)	No. 20	Gauge control module connector A (32P)	No. 30
   	B-CAN L		No. 21		No. 31

   Is there continuity?

   YES 

   The B-CAN H wire and the B-CAN L wire are OK. Refer to the DTC shown on the display, then substitute or replace the control unit based on the instructions (see chart below).

   DTC	Operation for transmitting control unit
   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 body control module and the transmitting control unit.