Code No.C121A: Steering wheel sensor initialisation abnormal


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

OPERATION


Steering wheel sensor stores the neutral position learned by the 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.

DIAGNOSIS CODE SET CONDITION


the steering wheel sensor has not learned the neutral position

PROBABLE CAUSES



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 stored again.

Q. Is diagnosis code 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 ).

Q. Has the calibration succeeded?
Go to Step 4
After replacing the steering wheel sensor, carry out calibration of steering wheel sensor to make ASC-ECU relearn the neutral point.(Refer to GROUP 35C - On-vehicles service .) Then, go to Step 4.

STEP 4. Check whether the diagnosis code is stored again.

Q. Is diagnosis code No.C121A stored?
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 stored again.

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