DTC U0104: Lost Communication With Adaptive Cruise Control System (ACC) Control Module (A/T, With CAN gateway)

NOTE: Before you troubleshoot, review the General Troubleshooting Information .

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
U0104 Lost Communication With Adaptive Cruise Control System (ACC) Control Module

DTC (A/T)

CAN gateway system DTC check

-1. Turn the vehicle to the ON mode.

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

DTC Description	DTC
U0029-00 CAN Gateway F-CAN ch A Bus Off
U0047-00 CAN Gateway F-CAN ch B Bus Off
U3000-49 CAN Gateway Internal Failure

Is DTC U0029-00, U0047-00, and/or U3000-49 indicated?

YES

Go to the indicated DTC's troubleshooting in the CAN gateway system - Refer to: Communication Systems DTC Troubleshooting Index (V6, With CAN gateway) (2015-17), or Communication Systems DTC Troubleshooting Index (2018-19) .

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

Which result is indicated?

TCM (Bus A) is Not Available

Go to step 3.

TCM (Bus B) is Not Available

Go to step 5. Refer to: 5

ACC UNIT/MULTIPURPOSE CAMERA UNIT (Bus A) is Not Available

Go to step 7. Refer to: 7

TCM and ACC UNIT/MULTIPURPOSE CAMERA UNIT are Detected

Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals between the multipurpose camera unit, the CAN gateway, and the TCM.

Open wire check (F-CAN A_H line)

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

- 2. Disconnect the following connectors.

CAN gateway 24P connector

TCM 58P connector

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

Test condition	Vehicle OFF (LOCK) mode
	CAN gateway 24P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	CAN gateway 24P connector No. 14
Test point 2	TCM 58P connector No. 34

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

Is there continuity?

YES

The F-CAN A_H wire is OK. Go to step 4.

Repair an open in the F-CAN A_H wire between the CAN gateway and the TCM.

Open wire check (F-CAN A_L line)

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

Test condition	Vehicle OFF (LOCK) mode
	CAN gateway 24P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	CAN gateway 24P connector No. 15
Test point 2	TCM 58P connector No. 47

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

Is there continuity?

YES

The F-CAN A_L wire is OK. Update the TCM if it does not have the latest software , or substitute a known-good TCM , then recheck. If this DTC goes away and the TCM was updated, troubleshooting is complete. If this DTC goes away and the TCM was substituted, replace the original TCM .

Repair an open in the F-CAN A_L wire between the CAN gateway and the TCM.

Open wire check (F-CAN B_H line)

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

- 2. Disconnect the following connectors.

CAN gateway 24P connector

TCM 58P connector

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

Test condition	Vehicle OFF (LOCK) mode
	CAN gateway 24P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	CAN gateway 24P connector No. 11
Test point 2	TCM 58P connector No. 7

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

Is there continuity?

YES

The F-CAN B_H wire is OK. Go to step 6.

Repair an open in the F-CAN B_H wire between the CAN gateway and the TCM.

Open wire check (F-CAN B_L line)

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

Test condition	Vehicle OFF (LOCK) mode
	CAN gateway 24P connector: disconnected
	TCM 58P connector: disconnected
Test point 1	CAN gateway 24P connector No. 10
Test point 2	TCM 58P connector No. 20

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

Is there continuity?

YES

The F-CAN B_L wire is OK. Update the TCM if it does not have the latest software , or substitute a known-good TCM , then recheck. If this DTC goes away and the TCM was updated, troubleshooting is complete. If this DTC goes away and the TCM was substituted, replace the original TCM .

Repair an open in the F-CAN B_L wire between the CAN gateway and the TCM.

Open wire check (F-CAN A_H line)

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

- 2. Disconnect the following connectors.

CAN gateway 24P connector

Multipurpose camera unit 20P connector

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

Test condition	Vehicle OFF (LOCK) mode
	CAN gateway 24P connector: disconnected
	Multipurpose camera unit 20P connector: disconnected
Test point 1	CAN gateway 24P connector No. 14
Test point 2	Multipurpose camera unit 20P connector No. 2 - Refer to: Multipurpose Camera Unit Connector for Inputs and Outputs (2015-17), or Multipurpose Camera Unit Connector for Inputs and Outputs (2018-19)

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

Is there continuity?

YES

The F-CAN A_H wire is OK. Go to step 8.

Repair an open in the F-CAN A_H wire between the CAN gateway and the multipurpose camera unit.

Open wire check (F-CAN A_L line)

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

Test condition	Vehicle OFF (LOCK) mode
	CAN gateway 24P connector: disconnected
	Multipurpose camera unit 20P connector: disconnected
Test point 1	CAN gateway 24P connector No. 15
Test point 2	Multipurpose camera unit 20P connector No. 13 - Refer to: Multipurpose Camera Unit Connector for Inputs and Outputs (2015-17), or Multipurpose Camera Unit Connector for Inputs and Outputs (2018-19)

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

Is there continuity?

YES

The F-CAN A_L wire is OK. Update the multipurpose camera unit if it does not have the latest software , or substitute a known-good multipurpose camera unit , then recheck. If this DTC goes away and the multipurpose camera unit was updated, troubleshooting is complete. If this DTC goes away and the multipurpose camera unit was substituted, replace the original multipurpose camera unit .

Repair an open in the F-CAN A_L wire between the CAN gateway and the multipurpose camera unit.