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 (Refer to GROUP 54C -
Troubleshooting
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- 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 GROUP 35C -
On-vehicle Service).
- When the ACC/FCM-ECU is replaced, calibrate the radar (refer to ).
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OPERATION
ACC/FCM-ECU communicates with the steering wheel sensor via the CAN bus lines.
DIAGNOSIS CODE SET CONDITIONS
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
- Malfunction of the CAN bus line
- Neutral position of steering wheel sensor not learned
- Malfunction of the column switch assembly (Integrated with steering wheel sensor)
- Malfunction of the ACC/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 perform the CAN bus diagnosis.
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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 ).
On completion, go to Step 2.
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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 GROUP 35C -
Troubleshooting <Steering
Wheel Sensor>, Diagnosis Function).
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Q.
Is the diagnosis code set?
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Troubleshoot the steering wheel sensor diagnosis code (Refer to GROUP 35C -
Troubleshooting <Steering
Wheel Sensor>, Diagnosis Code Chart).
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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 GROUP 35C -
On-vehicle
Service, 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 ACC/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)Press the ACC ON/OFF switch to turn the ACC system to ON.
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(5)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 stored again.
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Check again if the diagnosis code is set in the ACC/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)Press the ACC ON/OFF switch to turn the ACC system to ON.
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(5)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 ACC/FCM-ECU (Refer to ).
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Intermittent malfunction (Refer to GROUP 00 -
How to Cope with Intermittent
Malfunction).
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