DTC Advanced Diagnostics: U0029
DTC U0029:F-CAN Malfunction (BUS-OFF) (ACM System)

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 engine mount control unit does not receive the signals via the F-CAN lines for a set time, the engine mount control unit detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Execution
Continuous
Sequence
None
Duration
3.5 seconds or more
DTC Type
One drive cycle, MIL off
OBD Status
N/A

Enable Conditions
Condition
Minimum
Maximum
Elapsed time since the battery voltage reaches to a specified value after the engine start/stop button is pressed to select the ON mode
3 seconds
–
Battery voltage [BATTERY]
10.0 V
–
No active DTCs set (prevents monitor from running)
P15AB
[ ]: HDS Parameter

Malfunction Threshold
The engine mount control unit does not receive any signals via the F-CAN lines for at least 3.5 seconds.

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
F-CAN circuit F-CAN_L line open
F-CAN circuit F-CAN_H line short to ground
F-CAN circuit F-CAN_L line short to ground
F-CAN circuit F-CAN_H line short to F-CAN circuit F-CAN_L line
Engine mount control unit internal circuit failure

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.