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DTC U128D (Automatic Lighting Control Unit) (2013 2014 2015)

DTC U128D  : Auto Light Control Unit Lost Communication With Gauge Control Module

DTC Description DTC
U128D Auto Light Control Unit Lost Communication With Gauge Control Module  

DTC (Automatic Lighting Control Unit)

NOTE:
  • If you have any loss of communication DTCs for the PCM, troubleshoot those DTCs first.
  • 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. 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
    U128D Auto Light Control Unit Lost Communication With Gauge Control Module  

    Is DTC U128D indicated?

    YES 

    Go to step 2.

    NO 

    Intermittent failure, the system is OK at this time. Check for loose or poor connections.

  2. Determine possible failure area (gauge control module power and ground, B CAN line)

    -1. Select B-CAN CONTROL UNITS INFORMATION from the BODY ELECTRICAL SYSTEM SELECT menu, and then select CHECK CONNECTED CONTROL UNITS.

    -2. Check the DETECT/NOT AVAILABLE information of the GAUGE CONTROL MODULE.

    Is DETECT indicated?

    YES 

    Go to step 8.

    NO 

    Go to step 3.

  3. Fuse check

    -1. Check the following fuses.

    Fuse No. A29 (10 A)
    Location Under-hood fuse/relay box
    Fuse No. B5 (7.5 A)
    Location Under-dash fuse/relay box

    Is each fuse OK?

    YES 

    Go to step 4.

    NO 

    Replace the fuse. If the fuse blows again, repair a short to ground in the No. A29 (10 A) and/or the No. B5 (7.5 A) fuse circuit(s).

  4. Open wire check (+B BACK UP line)

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

    -2. Disconnect the following connector.

    Gauge control module 32P connector

    -3. Measure the voltage between test points 1 and 2.

    Test condition OFF mode
    Gauge control module 32P connector: disconnected
    Test circuit +B BACK UP
    Test point 1 Gauge control module 32P connector No. 1 (WHT)
    Test point 2 Body ground
    GHH462690Courtesy of HONDA, U.S.A., INC.

    Is there battery voltage?

    YES 

    The +B BACK UP wire is OK. Go to step 5.

    NO 

    Repair an open or high resistance in the wire.

  5. Open wire check (IG1 METER line)

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

    -2. Measure the voltage between test points 1 and 2.

    Test condition ON mode
    Gauge control module 32P connector: disconnected
    Test circuit IG1 METER
    Test point 1 Gauge control module 32P connector No. 2 (BRN)
    Test point 2 Body ground
    GHH462691Courtesy of HONDA, U.S.A., INC.

    Is there battery voltage?

    YES 

    The IG1 METER wire is OK. Go to step 6.

    NO 

    Repair an open or high resistance in the wire.

  6. Open wire check (GND lines)

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

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

    Test condition OFF mode
    Gauge control module 32P connector: disconnected
    Test circuit GND
    Test point 1 Gauge control module 32P connector No. 16 (GRY)
    Test point 2 Body ground
    Test circuit GND
    Test point 1 Gauge control module 32P connector No. 32 (BRN)
    Test point 2 Body ground
    GHH462692Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    The GND wires are OK. Go to step 7.

    NO 

    Repair an open or high resistance in the ground wire or poor ground (G502, G503).

  7. Open wire check (B CAN lines)

    -1. Disconnect the following connector.

    Automatic lighting control unit/sensor 7P connector

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

    Test condition OFF mode
    Gauge control module 32P connector: disconnected
    Automatic lighting control unit/sensor 7P connector: disconnected
    Test circuit B CAN-H
    Test point 1 Automatic lighting control unit/sensor 7P connector No. 6 (PNK)
    Test point 2 Gauge control module 32P connector No. 7 (PNK)
    GHH462693Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    An open or poor connection in the B CAN-L wire between the gauge control module and the automatic lighting control unit/sensor.

    NO 

    An open or poor connection in the B CAN-H wire between the gauge control module and the automatic lighting control unit/sensor.

  8. Open wire check (B CAN lines)

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

    -2. Disconnect the following connector.

    Gauge control module 32P connector
    Automatic lighting control unit/sensor 7P connector

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

    Test condition OFF mode
    Gauge control module 32P connector: disconnected
    Automatic lighting control unit/sensor 7P connector: disconnected
    Test circuit B CAN-H
    Test point 1 Automatic lighting control unit/sensor 7P connector No. 6 (PNK)
    Test point 2 Gauge control module 32P connector No. 7 (PNK)
    GHH462694Courtesy of HONDA, U.S.A., INC.

    Is there continuity?

    YES 

    An open or poor connection in the B CAN-L wire between the gauge control module and the automatic lighting control unit/sensor.

    NO 

    An open or poor connection in the B CAN-H wire between the gauge control module and the automatic lighting control unit/sensor.

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