Code No. C1781: SAS internal fail
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- 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 column switch assembly (Integrated with steering wheel sensor) is replaced, calibrate the steering wheel sensor (Refer to On-vehicle Service
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- When the FCM-ECU is replaced, calibrate the radar (refer to ).
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OPERATION
FCM-ECU communicates with the steering wheel sensor via the CAN bus lines.
DIAGNOSIS CODE SET CONDITION
This diagnosis code is set when the abnormality below is detected:
- Abnormality in steering wheel sensor signal
- The steering wheel sensor has not learned the neutral position yet.
PROBABLE CAUSES
- The CAN bus line is defective.
- Neutral position of steering wheel sensor not learned
- Malfunction of the column switch assembly (Integrated with steering wheel sensor)
- Malfunction of the FCM-ECU
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STEP 1. M.U.T.-III CAN bus diagnostics.
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 2.
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 Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ).
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STEP 2. Use M.U.T.-III to confirm a diagnosis code of other systems.
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Check if the diagnosis code is set in the steering wheel sensor (Refer to Diagnosis Code Chart ).
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Q.
Is the diagnosis code set?
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Troubleshoot the steering wheel sensor diagnosis code (Refer to Diagnosis Code Chart ). Then go to Step 4.
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Go to Step 3.
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STEP 3. Steering wheel sensor calibration
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Perform calibration of steering wheel sensor (Refer to Steering Wheel Sensor Calibration ).
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Q.
Has the calibration succeeded?
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Go to Step 4.
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Replace the column switch assembly (Integrated with steering wheel sensor) (Refer to GROUP 54A - Column Switch ).
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STEP 4. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set in the FCM-ECU.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(4)On completion, check that the diagnosis code is set again.
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Q.
Is diagnosis code No. C1781 set?
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Go to Step 5.
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This diagnosis is complete.
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STEP 5. M.U.T.-III data list.
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Check the following data list (Refer to ).
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- Item No.25: Steering angle sensor state
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Q.
Is the check result normal?
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Go to Step 6.
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Replace the column switch assembly (Integrated with steering wheel sensor) (Refer to GROUP 54A - Column Switch ).
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STEP 6. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set in the FCM-ECU.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(4)On completion, check that the diagnosis code is set again.
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Q.
Is diagnosis code No. C1781 set?
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Replace the FCM-ECU (Refer to ).
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
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