DTC Advanced Diagnostics: U0146 (A/T System)
DTC U0146 : PF-CAN A Malfunction (TCM - CAN Gateway)
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 information is not sent from the CAN gateway via the F-CAN lines and this condition continues for a specified time or when the information sent from the CAN gateway 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 | 2.5 seconds or more |
| DTC Type | One drive cycle, MIL on, 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 CAN gateway via F-CAN lines for at least 1 second.
- The information sent from the CAN gateway is abnormal at least 100 times.
Possible Cause
- PF-CAN circuit PF-CAN A_H line open
- PF-CAN circuit PF-CAN A_L line open
- PF-CAN circuit PF-CAN A_H line short to ground
- PF-CAN circuit PF-CAN A_L line short to ground
- CAN gateway internal circuit failure
- TCM internal circuit failure
Confirmation Procedure
Operating Condition
Turn the vehicle to the ON mode, and wait for several seconds.
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.