DTC U0129-00 (VSA Control Unit)

DTC U0129-00 : CAN Communication Failure with AHB/ESB/EBB

NOTE

Initial Diagnosis:
The initial on-board diagnosis occurs right after the vehicle condition is turned to the ON mode, and the ABS, VSA, and brake system indicator (amber) come on, and continues until the indicator goes off.
Regular Diagnosis:
The regular on-board diagnosis begins right after the ABS, VSA, and brake system indicator (amber) go off, and it continues until the vehicle condition is turned to the OFF (LOCK) mode.
Review "How to Troubleshoot the VSA 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 10 V or more Operating Condition: Start the engine. Test-drive the vehicle at 7 mph (10 km/h) or more for at least 2 seconds.(Drive the vehicle on the road, not on a lift. Be careful of the surrounding traffic conditions.)
Execution	Regular Diagnosis
Duration	About 2 seconds
DTC Type	1 drive cycle Brake system indicator (amber) on
Fail Safe Action	Stop automatic brake hold control function Stop ACC function* 2 Stop ACC function* 2
Possible Cause	Open between the VSA modulator-control unit and the electric brake booster (F-CAN A_H, F-CAN A_L, F-CAN B_H, F-CAN B_L lines)* 1 Open between the VSA modulator-control unit and the CAN gateway (F-CAN A_H, F-CAN A_L, F-CAN B_H, F-CAN B_L lines)* 2 Open between the CAN gateway and the electric brake booster (F-CAN A_H, F-CAN A_L, F-CAN B_H, F-CAN B_L lines)* 2 Electric brake booster internal failure VSA modulator-control unit internal failure

*1: Without ACC

*2: With ACC