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

WARNING: This page is about a different car, the 2011 Acura TL, 2010 Acura TL, and 2009 Acura TL. However, it is still accessible from the selected car via links, so may be relevant.

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 SPECIFICATION CHART

Control Unit

Connector

Passenger's MICU

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

Door multiplex control unit

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 B (12P)

Power seat control unit

Connector A (40P)

HandsFreeLink control unit

28P connector

AcuraLink control unit⁽⁵⁾

Connector A (32P)

⁽¹⁾	Without keyless access system

⁽²⁾	With keyless access system

⁽³⁾	Without navigation system

⁽⁴⁾	With navigation system

⁽⁵⁾	With AcuraLink

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 MICU INPUT TEST )
Door multiplex control unit input test (see POWER WINDOW MASTER SWITCH INPUT TEST )
Gauge control unit input test (see GAUGE CONTROL MODULE INPUT TEST )
Power control unit input test (see POWER CONTROL UNIT )
Keyless access control unit input test (see CONTROL UNIT INPUT TEST )
Remote slot control unit input test (see REMOTE SLOT CONTROL UNIT )
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 )
Audio-navigation unit input test (see NAVIGATION 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

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair 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

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair 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

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there voltage?

YES -Repair 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/INSTALLATION )