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DTC C123B: Prolonged operation of ASC
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. 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 G and yaw rate sensor.
  • When the G and yaw rate sensor is replaced, always carry out calibration to make ASC-ECU learn the neutral point (Refer to ).
  • 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 ).
 
 
OPERATION
ASC-ECU controls ASC by calculating the data sent from the wheel speed sensor, the steering wheel sensor, and the G and yaw rate sensor.
 
 
 
DTC SET CONDITIONS
This diagnostic trouble code is set when ASC operates for a prolonged period.
noteWhen the vehicle runs on a slippery or rough road, or when the vehicle makes the steady turn, this diagnostic trouble code may be set.
 
 
 
PROBABLE CAUSES
  • Steering wheel sensor malfunction
  • G and yaw rate sensor malfunction
  • Improper installation of wheel speed sensor, steering wheel sensor, or G and yaw rate sensor
  • ASC-ECU malfunction
  • Different steering wheel
  • Wheel alignment not performed
 
 
 
 
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 C123B set?
Go to Step 3.
The procedure is complete.
 
STEP 3. Check the wheel speed sensor, and G and yaw rate sensor-related DTC.
Check that DTCs C100A, C1015, C1020, C102B, C1011, C101C, C1027, C1032, C1014, C101F, C102A, C1035, C1041, C1042, C1043, C1044, C1219, C2205, C123C, and C2204 are also set.
Are DTCs C100A, C1015, C1020, C102B, C1011, C101C, C1027, C1032, C1014, C101F, C102A, C1035, C1041, C1042, C1043, C1044, C1219, C2205, C123C, and C2204 also set?
Carry out the diagnosis for the relevant diagnostic trouble codes, and then go to Step 9.
Go to Step 4.
 
STEP 4. Using scan tool MB991958, check the data list
Check the following data list (Refer to .)
  • Item 06: Yaw rate sensor
  • Item 08: Lateral G sensor
  • Item 09: G sensor
Is the check result normal?
Go to Step 5.
Go to Step 8.
 
STEP 5. Check of steering wheel sensor installation status
Check that the steering wheel sensor is installed correctly.
Is the check result normal?
Go to Step 6.
Install the steering wheel sensor correctly (Refer to ). Then go to Step 6.
 
STEP 6. Wheel alignment check
Refer to GROUP 33 - On-vehicles service/Front Wheel Alignment Check and Adjustment .
Is the check result normal?
After checking the wheel alignment, perform the calibration of steering wheel sensor to make ASC-ECU relearn the neutral point (Refer to ). Then go to Step 7.
After adjusting the wheel alignment, perform the calibration of steering wheel sensor to make ASC-ECU relearn the neutral point (Refer to ). Then go to Step 7.
 
STEP 7. Using scan tool MB991958, check the data list
Check the following data list (Refer to ).
  • Item 05: Steering angle sensor
Is the check result normal?
Go to Step 8.
Replace the steering wheel sensor (Refer to ). Then go to Step 9.
 
STEP 8. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Drive the vehicle at 12mph (20 km/h) or higher.
Does ASC unnecessary activation occur or is DTC C123B set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 9.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
 
STEP 9. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Drive the vehicle at 12mph (20 km/h) or higher.
Does ASC unnecessary activation occur or is DTC C123B set?
Return to Step 1.
The procedure is complete.