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Home >> Acura >> 2022 >> ILX >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Multiplex Integrated Control Unit (MICU) - DTC Diagnostics (Except Hybrid) >> DTC Troubleshooting >> DTC U1280 MICU (Multiplex Integrated Control Unit) (2013 2014 2015)

DTC U1280 MICU (Multiplex Integrated Control Unit) (2013 2014 2015)

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

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

DTC (MICU)

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

    -1. Clear the DTCs with the HDS.

    -2. Press the engine start/stop button to select the OFF mode and then the ON mode.

    -3. Wait for at least 6 seconds.

    -4. 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. Press the engine start/stop button to select the OFF 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 32P connector
    Climate control unit Connector A (28P)
    Power window master switch 37P connector
    Automatic lighting control unit/sensor 7P connector
    Keyless access control unit Connector B (32P)
    Backup control unit 40P connector
    Power control unit Connector C (36P)
    AcuraLink control unit 32P connector
    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

    -1. Press the engine start/stop button to select the OFF mode.

    -2. Disconnect the following connectors.

    Under-dash fuse/relay box connector K (12P)
    Under-dash fuse/relay box connector M (7P)
    Under-dash fuse/relay box connector Q (16P)

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

    Test condition OFF mode
    Under-dash fuse/relay box connector K (12P): disconnected
    Under-dash fuse/relay box connector M (7P): disconnected
    Under-dash fuse/relay box connector Q (16P): disconnected
    Test circuit B CAN-L
    Test point 1 Under-dash fuse/relay box connector K (12P) No. 1 (BLU)
    Test point 2 Body ground
    Test circuit B CAN-H
    Test point 1 Under-dash fuse/relay box connector K (12P) No. 2 (PNK)
    Test point 2 Body ground
    GHH472858Courtesy of HONDA, U.S.A., INC.

    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

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

    Test condition OFF mode
    Under-dash fuse/relay box connector K (12P): disconnected
    Under-dash fuse/relay box connector M (7P): disconnected
    Under-dash fuse/relay box connector Q (16P): disconnected
    Test circuit B CAN-L
    Test point 1 Under-dash fuse/relay box connector M (7P) No. 1 (BLU)
    Test point 2 Body ground
    Test circuit B CAN-H
    Test point 1 Under-dash fuse/relay box connector M (7P) No. 2 (PNK)
    Test point 2 Body ground
    GHH472859Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short to ground in the B CAN wires.

    NO 

    Go to step 5.

  5. Shorted wire check (B CAN lines) 3

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

    Test condition OFF mode
    Under-dash fuse/relay box connector K (12P): disconnected
    Under-dash fuse/relay box connector M (7P): disconnected
    Under-dash fuse/relay box connector Q (16P): disconnected
    Test circuit B CAN-L
    Test point 1 Under-dash fuse/relay box connector Q (16P) No. 6 (BLU)
    Test point 2 Body ground
    Test circuit B CAN-H
    Test point 1 Under-dash fuse/relay box connector Q (16P) No. 5 (PNK)
    Test point 2 Body ground
    GHH472860Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short to ground in the B CAN wires.

    NO 

    Go to step 6.

  6. Shorted wire check (B CAN-L to B CAN-H line) 1

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

    Test condition OFF mode
    Under-dash fuse/relay box connector K (12P): disconnected
    Under-dash fuse/relay box connector M (7P): disconnected
    Under-dash fuse/relay box connector Q (16P): disconnected
    Test circuit B CAN-L, B CAN-H
    Test point 1 Under-dash fuse/relay box connector K (12P) No. 1 (BLU)
    Test point 2 Under-dash fuse/relay box connector K (12P) No. 2 (PNK)
    GHH472861Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short in the B CAN-L to B CAN-H wire.

    NO 

    Go to step 7.

  7. Shorted wire check (B CAN-L to B CAN-H line) 2

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

    Test condition OFF mode
    Under-dash fuse/relay box connector K (12P): disconnected
    Under-dash fuse/relay box connector M (7P): disconnected
    Under-dash fuse/relay box connector Q (16P): disconnected
    Test circuit B CAN-L, B CAN-H
    Test point 1 Under-dash fuse/relay box connector M (7P) No. 1 (BLU)
    Test point 2 Under-dash fuse/relay box connector M (7P) No. 2 (PNK)
    GHH472862Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    Repair a short in the B CAN-L to B CAN-H wire.

    NO 

    Go to step 8.

  8. Shorted wire check (B CAN-L to B CAN-H line) 3

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

    Test condition OFF mode
    Under-dash fuse/relay box connector K (12P): disconnected
    Under-dash fuse/relay box connector M (7P): disconnected
    Under-dash fuse/relay box connector Q (16P): disconnected
    Test circuit B CAN-L, B CAN-H
    Test point 1 Under-dash fuse/relay box connector Q (16P) No. 6 (BLU)
    Test point 2 Under-dash fuse/relay box connector Q (16P) No. 5 (PNK)
    GHH472863Courtesy of HONDA, U.S.A., INC.

    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 .

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