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DTC C121A: Steering Wheel Sensor Initialization
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be stored. Prior to this diagnosis, diagnose the CAN bus lines.
  • Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
  • When the steering wheel sensor is replaced, calibrate the steering wheel sensor (Refer to GROUP 35C - On-vehicle Service ), and reset the steering wheel sensor correction amount stored in the AWC-ECU. (Item No. 1: SAS adjusted value ).
 
 
OPERATION
Steering wheel sensor stores the neutral position learned by the scan tool (M.U.T.-III). When the neutral position has not been learned, the steering wheel sensor outputs the signal indicating that the learning has not been performed.
 
 
DTC SET CONDITION
This DTC is stored when the abnormality below is detected:
  • The steering wheel sensor has not learned the neutral position
 
 
PROBABLE CAUSES
  • Steering wheel sensor neutral point not learned
  • Malfunction of steering wheel sensor
  • Malfunction of AWC-ECU

 
 
DIAGNOSTIC PROCEDURE
STEP 1. Scan tool (M.U.T.-III) CAN bus diagnostics.
Use scan tool (M.U.T.-III) to perform the CAN bus diagnosis.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - Diagnosis, Can Bus Diagnostics Table ). After repairing the CAN bus line, go to Step 2 .
 
STEP 2. Check whether the DTC is stored again.
Is DTC No.C121A stored?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Steering wheel sensor calibration.
Perform calibration of the steering wheel sensor (Refer to GROUP 35C - On-vehicle Service ).
Has the calibration succeeded?
Go to Step 4.
Replace the steering wheel sensor (Refer to GROUP 35C - Steering Wheel Sensor ). Then, go to Step 4.
 
STEP 4. Check whether the DTC is stored again.
Is DTC No.C121A stored?
Replace the AWC-ECU (Refer to ). Then, go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
 
STEP 5. Check whether the DTC is stored again.
Is DTC No.C121A stored?
Return to Step 1.
This diagnosis is complete.