Multiplex Integrated Control Unit

Control System DTCs

DTC Troubleshooting: U1280

DTC U1280 : Communication Bus Line Error (BUS-OFF)

NOTE:
* Refer to the Electrical Wiring Diagrams for the location of the under-dash fuse/relay box connectors.
* If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A.

1. Problem verification:

-1. Clear the DTCs with the HDS.

-2. Turn the ignition switch to LOCK (0) and then back to ON (II).

-3. Wait for at least 6 seconds.

-4. Check for DTCs with the HDS.

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 ignition switch to LOCK (0).

-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.










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. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connector.






-3. Check for continuity between test points 1 and 2 individually.














Is there continuity?
-YES- Repair a short to ground in the B CAN wires.
-NO- The B CAN wires are OK. 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.










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 Under-Dash Fuse/Relay Box Removal and Installation.