DTC Advanced Diagnostics: U0029 (298) (Generator Motor Control Module)
DTC U0029 (298): F-CAN Malfunction (Generator Motor Control Module Bus-Off)
General Description
The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using F-CAN A_H and F-CAN A_L lines. If the bus-off occurs due to an open or a short circuit in the F-CAN line is detected for a prescribed time, the CAN controller in the motor control module detects a malfunction and a DTC is stored.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 2.5 seconds or more |
| DTC Type | Two drive cycles, MIL on, POWER SYSTEM indicator on, 12 volt battery charging system indicator off |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Elapsed time since the 12 volt battery voltage reaches to a specified value after the vehicle condition is turned to the ON mode | 50 milliseconds | - |
| 12 volt battery voltage | 10.2 V | - |
Malfunction Threshold
The F-CAN line bus-off continues for at least 2.5 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 A_H line open
- F-CAN circuit F-CAN A_L line open
- F-CAN circuit F-CAN A_H line short to ground
- F-CAN circuit F-CAN A_L line short to ground
- Unit communicating on F-CAN internal circuit failure
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the motor control module memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on, the POWER SYSTEM indicator comes on and a Confirmed DTC and the freeze data are stored in the motor control module memory.
Conditions for clearing the DTC
The MIL and the POWER SYSTEM indicator is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the POWER SYSTEM indicator, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.