DTC Advanced Diagnostics: U0038
DTC U0038:PT-CAN Malfunction (TCM ECU BUS-OFF)

General Description

The controller area network (CAN) transmits/receives pulse signals to/from the control modules simultaneously by using two signal lines (TM-CAN_H and TM-CAN_L). When the information is not sent from the transmission control module (TCM) unit via the TM-CAN lines and this condition continues for a specified time or when the information sent from the TCM unit is abnormal and this condition continues for a specified cycle, the powertrain control module (PCM) detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
1.5 seconds or more
DTC Type
One drive cycle, MIL on

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

Malfunction Threshold
One of these conditions is met:
The PCM does not receive any signals via the TM-CAN lines for at least 1.5 seconds.
The information sent from the TCM unit is abnormal at least 20 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.
TCM failure (include fuse fall-outs)
TM-CAN circuit TM-CAN_H line open
TM-CAN circuit TM-CAN_L line open
TM-CAN circuit TM-CAN_H line short to ground
TM-CAN circuit TM-CAN_L line short to ground
PCM internal circuit failure

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

Conditions for clearing the DTC
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 or by disconnecting the 12 volt battery.