DTC Advanced Diagnostics: U0029
DTC U0029:F-CAN Malfunction (F-CAN Bus OFF)

General Description

The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (F-CAN_H and F-CAN_L). When the transmission control module (TCM) cannot send the signals via the F-CAN lines for a set time, the 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 on, Shift position indicator blinks

Enable Conditions
Condition
Minimum
Maximum
Elapsed time after the vehicle condition is turned to the ON mode
3 seconds
–
12 volt battery voltage [Battery Voltage]
10.0 V
–
[ ]: HDS Parameter

Malfunction Threshold
The TCM cannot send any signals via the F-CAN lines for at least 1 second.

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_H line open*1
F-CAN circuit F-CAN_L line open*1
F-CAN circuit F-CAN A_H line open*2
F-CAN circuit F-CAN A_L line open*2
F-CAN circuit F-CAN_H line short to ground*1
F-CAN circuit F-CAN_L line short to ground*1
F-CAN circuit F-CAN A_H line short to ground*2
F-CAN circuit F-CAN A_L line short to ground*2
TCM internal circuit failure

*1: Without CAN gateway
*2: With CAN gateway

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, the MIL comes on, the shift position indicator blinks, and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the TCM memory.

Conditions for clearing the DTC
The shift position indicator comes off by turning the vehicle to the OFF (LOCK) mode. The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.