DTC U1280: Communication bus line error (BUS-OFF) (MICU (Multiplex Integrated Control Unit))

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, .

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
   U1280 Communication bus line error (BUS-OFF)

   Is DTC U1280 indicated?

   YES 

   Go to step 2.

   NO 

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

2. B-CAN related units check:

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

   - 2. Disconnect the appropriate connector at each control unit in the table one at a time. Turn the vehicle to the ON mode, clear the DTC, then recheck for DTCs after each unit is disconnected.

   Control Unit	Connector
   Gauge control module	32P connector
   Climate control unit	32P connector
   Automatic lighting control unit/sensor	7P connector
   Keyless access control unit (with keyless access system)	Connector C (20P)
   Immobilizer-keyless control unit (without keyless access system)	7P connector
   Audio-navigation unit (with navigation)	Connector B (20P)
   Audio unit (with display audio)	Connector B (20P)
   Audio unit (with color audio)	Connector C (24P)

   Clear DTCs

   DTC Description	DTC
   U1280 Communication bus line error (BUS-OFF)

   Is DTC U1280 indicated with each individual unit disconnected?

   YES 

   Leave the connectors disconnected, and go to step 3.

   NO 

   Replace the control unit that was disconnected when DTC U1280 did not reset.

3. Shorted wire check (B-CAN lines):

   - 1. Disconnect the following connector.

   Under-dash fuse/relay box connector G (10P)

   - 2. Check for continuity between test points 1 and 2 individually.

   Test condition	Vehicle OFF (LOCK) mode. Under-dash fuse/relay box connector G (10P): disconnected.
   Test point 1	Under-dash fuse/relay box connector G (10P) No. 2
   Test point 2	Body ground

   Test point 1	Under-dash fuse/relay box connector G (10P) No. 3
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to ground in the B-CAN wires.

   NO 

   Go to step 4.

4. Shorted wire check (B-CAN_L to B-CAN_H line):

   - 1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode. Under-dash fuse/relay box connector G (10P): disconnected.
   Test point 1	Under-dash fuse/relay box connector G (10P) No. 2
   Test point 2	Under-dash fuse/relay box connector G (10P) No. 3

   Is there continuity?

   YES 

   Repair a short in the B-CAN_L to B-CAN_H wire.

   NO 

   The B-CAN_L to B-CAN_H wire is OK. Faulty MICU; replace the under-dash fuse/relay box .