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DTC C123A: Abnormality in sensor calibration
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be stored. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
  • When the steering wheel sensor is replaced, always carry out calibration to make ASC-ECU learn the neutral point (Refer to ).
  • Do not drop or shock the ASC-ECU.
  • When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor, the G and yaw rate sensor and brake fluid pressure sensor (Refer to , and ).
 
 
CIRCUIT OPERATION
ASC-ECU stores the calibrated value of the G and yaw rate sensor, steering wheel sensor, and brake fluid pressure sensor.
 
 
 
DTC SET CONDITIONS
This diagnostic trouble code is stored when the calibrated value for each sensor stored in ASC-ECU is not within the predetermined range.
  • Abnormality in neutral position of the G and yaw rate sensor
  • Abnormality in neutral position of the steering wheel sensor
 
 
 
PROBABLE CAUSES
  • ASC-ECU malfunction
  • External noise interference
  • Improper installation of G and yaw rate sensor or steering wheel sensor
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines. (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.
 
STEP 2. DTC recheck after resetting CAN bus lines
Is DTC C123A stored?
Go to Step 3.
The procedure is complete.
 
STEP 3. Check if other DTC is stored.
Check whether the DTC related to G and yaw rate sensor and the steering wheel sensor is stored.
Is any diagnostic trouble code stored?
Diagnose for the DTC (Refer to ).
Go to Step 4.
 
STEP 4. G and yaw rate sensor calibration
Perform the calibration of G and yaw rate sensor (Refer to ).
Has the calibration succeeded?
Go to Step 5.
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ), and then go to Step 8.
 
STEP 5. Steering wheel sensor calibration
Perform the calibration of steering wheel sensor (Refer to ).
Has the calibration succeeded?
Go to Step 6.
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ), and then go to Step 8.
 
STEP 6. Brake fluid pressure sensor calibration
Perform the calibration of brake fluid pressure sensor (Refer to ).
Has the calibration succeeded?
Go to Step 7.
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ), and then go to Step 8.
 
STEP 7. Check whether the diagnostic trouble code is stored again.
Erase the DTC.
Is DTC C123A stored?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ), and then go to Step 8.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
 
STEP 8. Check whether the diagnostic trouble code is stored again.
Erase the DTC.
Is DTC C123A stored?
Return to Step 1.
The procedure is complete.