Code No.C121A: Steering Wheel Sensor Initialization <ASC>


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. 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 4WD-ECU. (Item No. 1: SAS adjusted value ).

OPERATION



DIAGNOSIS CODE SET CONDITION




  • 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 4WD-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.
Use M.U.T.-III to perform the CAN bus diagnosis.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). After repairing the CAN bus line, go to Step 2.

STEP 2. Check whether the diagnosis code is reset.

Q. Is diagnosis code No.C121A set?
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 ).

Q. 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 diagnosis code is reset.

Q. Is diagnosis code No.C121A set?
Replace the 4WD-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 diagnosis code is reset.

Q. Is diagnosis code No.C121A set?
Return to Step 1.
This diagnosis is complete.