DTC U128D: Backup Control Unit Lost Communication With Gauge Control Module (2013-15)

DTC (Backup Control Unit)

1. Problem verification:

   Clear the DTCs with the HDS.

   Clear DTCs

   - 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 Backup 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):

   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:

   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):

   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 (GRN)
   Test point 2	Body ground

   Courtesy 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):

   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

   Courtesy 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):

   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 (BLK)
   Test point 2	Body ground

   Test circuit	GND
   Test point 1	Gauge control module 32P connector No. 32 (BLK)
   Test point 2	Body ground

   Courtesy 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).

7. Open wire check (B CAN lines):

   Disconnect the following connector.

   Backup control unit 40P connector

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

   Test condition	OFF mode Gauge control module 32P connector: disconnected Backup control unit 40P connector: disconnected
   Test circuit	B CAN-H
   Test point 1	Backup control unit 40P connector No. 18 (PNK)
   Test point 2	Gauge control module 32P connector No. 7 (PNK)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   An open or poor connection in the B CAN-L wire between the MICU and the gauge control module.

   NO 

   An open or poor connection in the B CAN-H wire between the MICU and the gauge control module.

8. Open wire check (B CAN lines):

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

   - 2. Disconnect the following connectors.

   Gauge control module 32P connector

   Backup control unit 40P connector

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

   Test condition	OFF mode Gauge control module 32P connector: disconnected Backup control unit 40P connector: disconnected
   Test circuit	B CAN-H
   Test point 1	Backup control unit 40P connector No. 18 (PNK)
   Test point 2	Gauge control module 32P connector No. 7 (PNK)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   An open or poor connection in the B CAN-L wire between the backup control unit and the gauge control module.

   NO 

   An open or poor connection in the B CAN-H wire between the backup control unit and the gauge control module.