F-CAN Malfunction (Powertrain Control Module (PCM)-ABS)

DTC U0121: F-CAN Malfunction (Powertrain Control Module (PCM)-ABS)




General Description
The car area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (CANH and CANL).

When the information is not sent from the ABS modulator-control unit through the F-CAN and this condition continues for a settled time or more or when the information sent from the ABS modulator-control unit is abnormal and this condition continues for a settled cycle or more, the powertrain control module (PCM) detects a malfunction and a DTC is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
One of these conditions must be met.
- The PCM does not receive any signals from the ABS modulator-control unit for at least 1 second.
- The information sent from the ABS modulator-control unit is abnormal at least 20 times.

Diagnosis Details

Conditions for illuminating the indicator
When a malfunction is detected, the DTC and the freeze frame data are stored in the PCM memory. The MIL does not come on.

Conditions for clearing the DTC
The DTC and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.