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DTC C121A: SAS initialization
 
 
caution
  • Whenever the steering wheel sensor is replaced, always calibrate the sensor (Refer to GROUP 35C - Steering Wheel Calibration ). Then make the steering wheel sensor learn the compensation which the PHEV-ECU has stored (Item: Initialization, Item No. 3: Steering Angle offset reset ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
DTC SET CONDITIONS
The PHEV-ECU sets DTC C121A when the steering wheel sensor fails to learn the neutral position of the steering wheel.
 
 
 
PROBABLE CAUSES
  • Neutral position of steering wheel sensor not learned.
  • Malfunction of the steering wheel sensor.
  • Malfunction of the PHEV-ECU.
 
 

 
 
DIAGNOSIS
STEP 1. Steering wheel sensor calibration.
Perform calibration of steering wheel sensor (Refer to GROUP 35C - Steering Wheel Calibration ).
Has the calibration succeeded?
Go to Step 2.
After the steering wheel sensor is replaced, perform the steering wheel sensor calibration to make ASC-ECU learn the neutral point again (Refer to GROUP 35C - Steering Wheel Calibration ) and make the steering wheel sensor learn the compensation which the PHEV-ECU has stored (Item: Initialization, Item No. 3: Steering Angle offset reset ). Then go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check the DTC.
Is the DTC set?
Replace the PHEV-ECU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).