DTC Advanced Diagnostics: U0146 (K20C2 (CVT System))

DTC Advanced Diagnostics: U0146

DTC U0146: F-CAN 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	1.5 seconds or more
DTC Type	One drive cycle, MIL on, Shift position indicator blinks

Enable Conditions

Condition	Minimum	Maximum
12 volt battery voltage [Battery Voltage]	10.0 V	–

[ ]: HDS Parameter

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 1.5 seconds.
	The information sent from the CAN gateway 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.

	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
	CAN gateway internal circuit failure (include fuse fall-outs)
	TCM internal circuit failure

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.