DTC U0029-00, U0047-00 (Electric Brake Booster Control Unit: With ACC)

WARNING: This page is about a different car, the 2022 Honda Accord, 2021 Honda Accord, 2020 Honda Accord, 2019 Honda Accord, and 2018 Honda Accord. However, it is still accessible from the selected car via links, so may be relevant.

DTC U0029-00 : CAN Communication Failure (Ch1 Bus OFF)DTC U0047-00 : CAN Communication Failure (Ch2 Bus OFF)

NOTE:

Before you troubleshoot, review the general troubleshooting information .
Troubleshoot any PGM-FI system DTCs first. .
This DTC is stored by communication failure between the F-CAN line and the electric brake booster. When DTC U0029-00 is indicated, the F-CAN line has already returned to normal. Check for loose terminals and poor connections in the connectors. If the connectors are OK, clear the DTC and following this troubleshooting.

DTC Description	DTC	Freeze Frame
U0029-00 CAN Communication Failure (Ch1 Bus OFF)
U0047-00 CAN Communication Failure (Ch2 Bus OFF)

DTC (Electric brake booster)

CAN gateway system DTC check

-1. Check for CAN gateway system DTCs with the HDS.

DTC Description	DTC

DTC (CAN gateway)

Is DTC indicated?

YES

Go to indicated DTC's troubleshooting .

Go to step 2.

F-CAN circuit communication check
-1. Select the FUNCTION TEST in the CAN gateway with the HDS, then select the F-CAN Bus Connected Unit Check.

F-CAN Bus Connected Unit Check

Does the CAN gateway detect the electric brake booster Bus channels A and B?

Bus A is Not Available

Go to step 3.

Bus B is Not Available

Go to step 4.

Bus A and B are Available

Check for loose terminals and poor connections in the electric brake booster connector. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or replace the electric brake booster.

Open wire check (F-CAN A_H, F-CAN A_L lines)

-1. Turn the vehicle to the OFF (LOCK) mode with driver's door open.

-2. Wait for 3 minutes.

NOTE: Do not close the driver's door.

-3. Disconnect the following connectors.

Electric brake booster 26P connector

CAN gateway 16P connector

-4. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	Electric brake booster 26P connector: disconnected
	CAN gateway 16P connector: disconnected
Test point 1	Electric brake booster 26P connector No. 26
Test point 2	CAN gateway 16P connector (female terminals) No. 3:

Test point 1	Electric brake booster 26P connector No. 18
Test point 2	CAN gateway 16P connector (female terminals) No. 11:

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

Is there continuity?

YES

The F-CAN A_H and F-CAN A_L wires are OK. Check for loose terminals and poor connections in the electric brake booster connector. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or replace the electric brake booster.

Repair an open in the wire between the electric brake booster and the CAN gateway.

Open wire check (F-CAN B_H, F-CAN B_L lines)