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DTC C123C: Sensor cluster malfunction
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • 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 ).
 
 
OPERATION
ASC-ECU monitors if the output of G and yaw rate sensor is normal or not.
 
 
 
DTC SET CONDITIONS
This DTC is set if any malfunction below is found:
  • The output value of lateral G and yaw rate is abnormal.
  • When abnormality is detected by comparing the value output from the lateral G and yaw rate with the one from the steering wheel sensor and wheel speed sensor
 
 
 
PROBABLE CAUSES
  • Steering wheel sensor malfunction
  • Improperly installed steering wheel sensor
  • Malfunction of wheel speed sensor
  • ASC-ECU malfunction
  • External noise interference
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool MB991958 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 No.C123C set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Check the other sensor-related DTC.
Use scan tool MB991958 to check whether the wheel speed sensor-related or steering wheel sensor-related DTC is set or not.
Is the DTC set?
Troubleshoot for the relevant DTC (Refer to ).
Go to Step 4.
 
STEP 4. Check whether the ASC-ECU is installed properly.
Check whether the ASC-ECU is installed correctly. Refer to .
Is the check result normal?
Execute "Lateral G sensor calibration" on "Special function". After the calibration is performed (Refer to ) , turn the ignition switch from "OFF" to "ON". Then go to Step 5.
Install the ASC-ECU properly, and execute "Lateral G sensor calibration" on "Special function". After the calibration is performed (Refer to ) , turn the ignition switch from "OFF" to "ON". Then go to Step 5.
 
STEP 5. Scan tool MB991958 data list
Check the following data list (Refer to ).
  • Item 06: Yaw rate sensor
  • Item 08: Lateral G sensor
Is the check result normal?
Go to Step 6.
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ), and then go to Step 10.
 
STEP 6. Steering wheel sensor installation check
Check that the steering wheel sensor is installed correctly.
Is the check result normal?
Go to Step 7.
Reinstall the steering wheel sensor correctly (Refer to ), and then go to Step 7.
 
STEP 7. Wheel alignment check
Refer to <Front> or <Rear>.
Is the check result normal?
After checking the wheel alignment, carry out calibration of steering wheel sensor to make ASC-ECU relearn the neutral point (Refer to ). Then go to Step 8.
After adjusting the wheel alignment, carry out calibration of steering wheel sensor to make ASC-ECU relearn the neutral point (Refer to ). Then go to Step 8.
 
STEP 8. Scan tool MB991958 data list
Check the following data list (Refer to ).
  • Item 05: Steering angle sensor
Is the check result normal?
Go to Step 9.
Replace the steering wheel sensor (Refer to ), and then go to Step 9.
 
STEP 9. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn the steering wheel to either right or left at 20 km/h (12 mph) or more.
noteThe ASC warning/operation light and the ASC OFF light may remain on until the vehicle speed reaches approx. 10 km/h (6 mph), then the steering wheel is turned to either right or left.
Is DTC No.C123C set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ), and then go to Step 10.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
 
STEP 10. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn the steering wheel to either right or left at 20 km/h (12 mph) or more.
noteThe ASC warning/operation light and the ASC OFF light may remain on until the vehicle speed reaches approx. 10 km/h (6 mph), then the steering wheel is turned to either right or left.
Is DTC No.C123C set?
Return to Step 1.
This diagnosis is complete.