DTC Advanced Diagnostics: U0122
DTC U0122:F-CAN Malfunction (Powertrain Control Module (PCM)-VSA Modulator-Control Unit)

General Description

The VSA modulator-control unit monitors the signal from the wheel speed sensors. The powertrain control module (PCM) receives wheel speed information from the VSA modulator-control unit via the F-CAN lines. If the status of CAN communication between the PCM and the VSA modulator-control unit is abnormal, the 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
Two drive cycles, MIL on

Enable Conditions
Condition
 
Vehicle
ON mode

Malfunction Threshold
The status of CAN communication between the PCM and the VSA modulator-control unit is abnormal for at least 1.5 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
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 during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

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.