DTC Troubleshooting: U1280
DTC U1280: Communication Bus Line Error (BUS-OFF)
DTC Description
DTC
U1280 B-CAN communication bus line error (BUS-OFF)
  

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

NOTE: Refer to the Electrical Wiring Diagrams for the location of the under-dash fuse/relay box connectors.

1.
Problem verification:

Problem verification
?1.
Clear the DTCs with the HDS.


?2.
urn 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
U1280 B-CAN 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:

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. Clear the DTC, then recheck for DTCs after each unit is disconnected.
Control Unit
Connector
Gauge control module
Connector A (32P)
Climate control unit
32P connector
Power window master switch
37P connector
Power seat control unit
Connector B (40P)
Power tailgate control unit
Connector A (14P)
Automatic lighting/rain sensor
5P connector
Automatic lighting control unit/sensor
7P connector
Audio unit without display audio
Connector B (20P)
Audio unit with display audio
Connector C (20P)
Audio-navigation unit
Connector C (20P)
Keyless access control unit
Connector B (28P)
Immobilizer-keyless control unit
7P connector
Multi-information display unit
Connector A (32P)

DTC Description
DTC
U1280 B-CAN 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:

Shorted wire check (B-CAN lines) 1
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connectors.
Under-dash fuse/relay box connector K (12P)
Under-dash fuse/relay box connector Q (16P)

?3.
Check for continuity between test points 1 and 2 individually.
Test condition
Vehicle OFF (LOCK) mode
Under-dash fuse/relay box connector K (12P): disconnected
Under-dash fuse/relay box connector Q (16P): disconnected
Test point 1
Under-dash fuse/relay box connector K (12P) No. 1
Test point 2
Body ground

Test point 1
Under-dash fuse/relay box connector K (12P) No. 2
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 lines) 2:

Shorted wire check (B-CAN lines) 2
?1.
Check for continuity between test points 1 and 2 individually.
Test condition
IG LOCK (0) or OFF mode
Under-dash fuse/relay box connector K (12P): disconnected
Under-dash fuse/relay box connector Q (16P): disconnected
Test point 1
Under-dash fuse/relay box connector Q (16P) No. 5
Test point 2
Body ground

Test point 1
Under-dash fuse/relay box connector Q (16P) No. 6
Test point 2
Body ground

Is there continuity?

     
YES
     
     
     
Repair a short to ground in the B-CAN wires.?
     
NO
     
     
     
The B-CAN wires are not shorted to ground. Go to step 5.
5.
Shorted wire check (B-CAN_L to B-CAN_H line) 1:

Shorted wire check (B-CAN_L to B-CAN_H line) 1
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Under-dash fuse/relay box connector K (12P): disconnected
Under-dash fuse/relay box connector Q (16P): disconnected
Test point 1
Under-dash fuse/relay box connector K (12P) No. 1
Test point 2
Under-dash fuse/relay box connector K (12P) No. 2

Is there continuity?

     
YES
     
     
     
Repair a short in the B-CAN_L to B-CAN_H wire.?
     
NO
     
     
     
Go to step 6.
6.
Shorted wire check (B-CAN_L to B-CAN_H line) 2:

Shorted wire check (B-CAN_L to B-CAN_H line) 2
?1.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Under-dash fuse/relay box connector K (12P): disconnected
Under-dash fuse/relay box connector Q (16P): disconnected
Test point 1
Under-dash fuse/relay box connector Q (16P) No. 5
Test point 2
Under-dash fuse/relay box connector Q (16P) No. 6

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.?