S-AWC (Super All Wheel Control)

DTC C121A: Steering Wheel Sensor System (neutral learning abnormality)

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.
- 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 On-vehicle Service Testing and Inspection ), and initialize the steering angle correction amount stored in AWC-ECU. (Item No.1: Steering angle correction amount initialization Actuator Test Reference Table .)

OPERATION

Steering wheel sensor stores the neutral position learned by the scan tool. 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 CONDITIONS

This DTC is set when it is detected that 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 CAN bus diagnostics

Using scan tool MB991958, diagnose the CAN bus lines.

Q. Is the check result normal?

YES Go to Step 3.
NO Repair the CAN bus lines. CAN Bus Diagnostics Chart.) After repairing the CAN bus line, go to Step 2.
STEP 2. Check whether the DTC is reset.

Q. Is DTC No. C121A set?

YES Go to Step 3.
NO This diagnosis is complete.
STEP 3. Steering wheel sensor calibration

Perform calibration of the steering wheel sensor. Testing and Inspection.)

Q. Has the calibration succeeded?

YES Go to Step 4.
NO Replace the steering wheel sensor. Service and Repair.) Then, go to Step 4.
STEP 4. Check whether the DTC is reset.

Q. Is DTC No. C121A set?

YES Replace the AWC-ECU.(Refer to Active Center Differential (ACD).) Then, go to Step 5.
NO Intermittent malfunction. How to Cope With Intermittent Malfunctions.)
STEP 5. Check whether the DTC is reset.

Q. Is DTC No. C121A set?

YES Return to Step 1.
NO This diagnosis is complete.