DTC U1280: 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 (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0) and then back to ON (II), or press the engine start/stop button to select the OFF mode and then the ON mode.
Wait for at least 6 seconds.
Check for DTCs with the HDS.
Is DTC U1280 indicated?

YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. Check for loose or poor connections, or worn/shorted wires. If the connections are good, check the battery condition (see BATTERY TEST ) and the charging system.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

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

Passenger's MICU

Passenger's under-dash fuse/relay box connector A (38P)

Door multiplex control unit

Power window master switch 37P connector

Gauge control module

32P connector

Immobilizer-keyless control unit⁽¹⁾

7P connector

Power control unit⁽²⁾

Connector C (36P)

Keyless access control unit⁽²⁾

Connector B (32P)

Remote slot control unit⁽²⁾

40P connector

Audio-navigation control unit⁽⁴⁾

Connector D (20P)

Audio unit⁽³⁾

Connector D (20P)

Climate control unit

Connector C (20P)

Power seat control unit

Connector B (40P)

HandsFreeLink control unit⁽³⁾

28P connector

AcuraLink control unit⁽⁵⁾

Connector A (32P)

BSI control unit⁽⁶⁾

16P connector

⁽¹⁾	Without keyless access system

⁽²⁾	With keyless access system

⁽³⁾	Without navigation

⁽⁴⁾	With navigation

⁽⁵⁾	USA models with navigation

⁽⁶⁾

With BSI

Is DTC U1280 indicated with each individual unit disconnected?

YES - Leave the connectors disconnected, and go to step 7.

NO - Go to the input test (or circuit troubleshooting) for the control unit that was disconnected when DTC U1280 did not reset, and perform all power and ground input tests. If the tests prove OK, replace that unit.

Passenger's MICU input test (see DTC U1283: DRIVER'S MICU LOST COMMUNICATION WITH PASSENGER'S MICU )
Door multiplex control unit (power window master switch) input test (see POWER WINDOW MASTER SWITCH INPUT TEST )
Gauge control module input test (see GAUGE CONTROL MODULE INPUT TEST )
Power control unit input test (see RF UNIT REPLACEMENT )
Keyless access control unit input test (see CONTROL UNIT INPUT TEST )
Remote slot control unit input test (see RF UNIT REPLACEMENT )
Immobilizer-keyless control unit input test (see IMMOBILIZER-KEYLESS CONTROL UNIT INPUT TEST )
Climate control unit power and ground circuit troubleshooting (see CLIMATE CONTROL POWER AND GROUND CIRCUIT TROUBLESHOOTING )
Power seat control unit input test (see POWER SEAT CONTROL UNIT INPUT TEST/REPLACEMENT )
HandsFreeLink control unit input test (see CONTROL UNIT INPUT TEST )
AcuraLink control unit input test (see ACURALINK CONTROL UNIT (XM RECEIVER) CONNECTOR FOR INPUTS AND OUTPUTS )
Audio unit input test (see AUDIO UNIT CONNECTOR FOR INPUTS AND OUTPUTS (WITH NAVIGATION) )
Audio-navigation unit input test (see NAVIGATION UNIT CONNECTOR FOR INPUTS AND OUTPUTS )
BSI control unit input test (see BLIND SPOT INFORMATION SYSTEM (BSI) CONTROL UNIT INPUTS AND OUTPUTS ).

Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
Remove the driver's dashboard undercover (see DRIVER'S DASHBOARD UNDERCOVER REMOVAL/INSTALLATION ).
Disconnect driver's under-dash fuse/relay box connector P (20P).
Check for continuity between driver's under-dash fuse/relay box connector P (20P) terminals No. 5 and No. 6.

Fig 1: Checking Continuity Between Driver's Under-Dash Fuse/Relay Box Connector P (20P) Terminals No. 5 And No. 6 With Connector End View
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short in the B-CAN wires.

NO - Go to step 11.
Check for continuity between body ground and driver's under-dash fuse/relay box connector P (20P) terminals No. 5 and No. 6 individually.

Fig 2: Checking Continuity Between Body Ground And Driver's Under-Dash Fuse/Relay Box Connector P (20P) Terminals No. 5 And No. 6 Individually
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to ground in the wire(s).

NO - Go to step 12.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
Measure the voltage between body ground and driver's under-dash fuse/relay box connector P (20P) terminals No. 5 and No. 6 individually.

Fig 3: Measuring Voltage Between Body Ground And Driver's Under-Dash Fuse/Relay Box Connector P (20P) Terminals No. 5 And No. 6 Individually
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there voltage?

YES - Repair a short to power in the wire(s).

NO - Faulty driver's MICU; replace the driver's under-dash fuse/relay box (see DRIVER'S UNDER-DASH FUSE/RELAY BOX (MICU) REMOVAL AND INSTALLATION ).