DTC U0122-00

DTC U0122-00: F-CAN Malfunction (Electric Servo Brake Control Unit Lost Communication With VSA Modulator-Control Unit)

NOTE:

Initial Diagnosis:
The initial on-board diagnosis occurs right after the vehicle condition is turned to the ON mode, and the brake system indicator (red or amber) comes on, and continues until the indicator goes off.
Regular Diagnosis:
The regular on-board diagnosis begins right after the brake system indicator (red or amber) goes off, and it continues until the vehicle condition is turned to the OFF (LOCK) mode.
Review "How to Troubleshoot the Electric Servo Brake System" before doing the DTC troubleshooting procedure.
Test-drive the vehicle according to local traffic conditions and regulations. Do not test-drive on a lift unless specified.
The possible causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

Confirmation Procedure	Basic Condition: 12 volt battery voltage 9.5 - 16.7 V Operating Condition: Turn the vehicle to the READY TO DRIVE mode.
Execution	Regular Diagnosis
Duration	About 1 second
DTC Type	1 drive cycle Brake system indicator (amber) on
Fail Safe Action	Stop brake assist function (re-diagnose at the next IG-ON) Stop deceleration assist brake cooperative control function (re-diagnose at the next IG-ON) Stop VSA assist cooperative control function (re-diagnose at the next IG-ON) Stop stall management function (re-diagnose at the next IG-ON) Stop regenerative brake function (re-diagnose at the next IG-ON)
Possible Cause	Open, Short to ground, Short to another wire, or Poor connection between the electric servo brake control unit and the CAN gateway (F-CAN A_H, F-CAN A_L, F-CAN B_H, F-CAN B_L lines) Open, Short to ground, Short to another wire, or Poor connection between the CAN gateway and the VSA modulator-control unit (F-CAN A_H, F-CAN A_L, F-CAN B_H, F-CAN B_L lines) VSA modulator-control unit internal failure Electric servo brake control unit internal failure