DTC Advanced Diagnostics: C0023-12
DTC C0023-12: Brake Diag Circuit ON Failure
NOTE
Initial Diagnosis:
The initial on-board diagnosis occurs right after the vehicle condition is turned to the ON mode, and the ABS/VSA indicator comes on, and continues until the indicator goes off.
Regular Diagnosis:
The regular on-board diagnosis begins right after the ABS/VSA indicator goes 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 9.6 - 16.5 V
No other DTCs detected
Brake pedal is released

With the Driving Pattern:
1.
Turn the vehicle to the ON mode, and release the brake pedal.
2.
Wait 2 seconds or more without pressing the brake pedal.
Execution
Regular Diagnosis
Duration
About 2 seconds
DTC Type
1 drive cycle
Brake system indicator (amber) on
Fail Safe Action
Stop automatic brake hold function
Stop ACC function*
Stop CMBS function*
Possible Cause
Relay circuit board failure
Short to ground between the VSA modulator-control unit and the relay circuit board (BRK LAMP line)
Open between the PCM and the brake pedal position switch (STOP SW line)
PCM internal failure
VSA modulator-control unit internal failure
*: With ACC