DTC Advanced Diagnostics: U0128
DTC U0128:F-CAN Malfunction (Powertrain Control Module (PCM)-Electric Parking Brake Control Unit)

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 powertrain control module (PCM) cannot receive the signals from the VSA modulator-control unit via the F-CAN lines for a set time, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
1 second or more
DTC Type
One drive cycle, MIL off

Enable Conditions
Condition
Minimum
Maximum
12 volt battery voltage [BATTERY]
10.0 V
–
[ ]: HDS Parameter

Malfunction Threshold
The PCM cannot receive any signals from the VSA modulator-control unit via the F-CAN lines for at least 1 second.

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
F-CAN circuit F-CAN B_H line open
F-CAN circuit F-CAN B_L line open
F-CAN circuit F-CAN B_H line short to ground
F-CAN circuit F-CAN B_L line short to ground
VSA modulator-control unit failure (include fuse fall-outs)
PCM 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 12 volt battery.