DTC Troubleshooting: U128D(Relay Control Module) (2016 2017 2018 2019 2020)

DTC U128D  : Relay Control Module Lost Communication With Gauge Control Module (VSP/NE Frame)

DTC (Relay Control Module)

NOTE:  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. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   -3. Wait for at least 6 seconds.

   -4. Check for DTCs with the HDS.

   DTC Description	DTC
   U128D Relay Control Module Lost Communication With Gauge Control Module (VSP/NE Frame)

   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 GAUGES from the BODY ELECTRICAL SYSTEM SELECT menu, and then select DATA LIST.

   Does the DATA LIST appear?

   YES 

   Go to step 5.

   NO 

   Go to step 3.

3. Fuse check

   -1. Check the following fuses.

   Fuse	No. C16 (10 A)
   Location	Under-hood fuse/relay box

   Fuse	No. D11 (10 A)
   Location	Driver's 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. C16 (10 A) and/or No. D11 (10 A) fuse circuit(s).

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

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Disconnect the following connector.

   Gauge control module connector A (32P)

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

   Test condition	Vehicle OFF (LOCK) mode Gauge control module connector A (32P): disconnected
   Test circuit	+B BACK UP
   Test point 1	Gauge control module connector A (32P) No. 1 (PNK)
   Test point 2	Body ground

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

   Is there battery voltage?

   YES 

   Repair an open or high resistance in the ground wire or poor ground (G501).

   NO 

   Repair an open or high resistance in the wire.

5. Open wire check (B-CAN_H line)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Disconnect the following connectors.

   Relay control module connector B (16P)

   Gauge control module connector A (32P)

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

   Test condition	Vehicle OFF (LOCK) modeRelay control module connector B (16P): disconnectedGauge control module connector A (32P): disconnected
   Test circuit	B-CAN_H
   Test point 1	Relay control module connector B (16P) No. 15 (RED)
   Test point 2	Gauge control module connector A (32P) No. 25 (RED)

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

   Is there continuity?

   YES 

   The B-CAN_H wire is OK. Go to step 6.

   NO 

   An open or poor connection in the B-CAN_H wire.

6. Open wire check (B-CAN_L line)

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

   Test condition	Vehicle OFF (LOCK) modeGauge control module connector A (32P): disconnectedRelay control module connector B (16P): disconnected
   Test circuit	B-CAN_L
   Test point 1	Relay control module connector B (16P) No. 16 (WHT)
   Test point 2	Gauge control module connector A (32P) No. 26 (WHT)

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

   Is there continuity?

   YES 

   The B-CAN_L wire is OK. Replace the relay control module .

   NO 

   An open or poor connection in the B-CAN_L wire.