DTC U0104 (A/T)

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DTC U0104: F-CAN Malfunction (TCM - ACC)

General Description

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

The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (H line and L line). When the information is not sent from the millimeter wave radar via the F-CAN lines and this condition continues for a specified time or when the information sent from the millimeter wave radar is abnormal and this condition continues for a specified cycle, the transmission control module (TCM) detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Continuous
Sequence	None
Duration	1 second or more
DTC Type	One drive cycle, MIL off, Shift position indicator blinks

Enable Conditions

Condition
Vehicle	ON mode

Malfunction Threshold

One of these conditions is met:

The TCM does not receive any signals from the millimeter wave radar via F-CAN lines for at least 1 second.
The information sent from the millimeter wave radar is abnormal at least 100 times.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

F-CAN circuit F-CAN E_H line open
F-CAN circuit F-CAN E_L line open
F-CAN circuit F-CAN E_H line short to ground
F-CAN circuit F-CAN E_L line short to ground
Millimeter wave radar internal circuit failure
TCM internal circuit failure

Confirmation Procedure

Operating Condition

Turn the vehicle to the ON mode, and wait for several seconds.

With the HDS

None.

Diagnosis Details

Conditions for setting the DTC

When a malfunction is detected, the shift position indicator blinks and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the TCM memory. The MIL does not come on.

Conditions for clearing the DTC

The shift position indicator comes off by turning the vehicle to the OFF (LOCK) mode. The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.