Code No. C1781: SAS internal fail

caution

If a diagnosis code is set, be sure to diagnose the CAN bus line.

DIAGNOSTIC FUNCTION

If the laser radar receives a signal indicating that an internal error occurs or the neutral position learning is not completed from the steering wheel sensor, diagnosis code No. C1781 is set. Diagnosis code No. C1394 may be set simultaneously.

CHECK CONDITION

When all the following conditions are satisfied.

After the ignition switch is turned ON, two or more seconds passed.
After the engine has started.

PROBABLE CAUSES

Steering wheel sensor calibration error
Malfunction or incorrect installation of the steering wheel sensor
Malfunction of the laser radar

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis.

Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

	Go to Step 2.

	Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).

STEP 2. Steering wheel sensor installation state check.

Check that the steering wheel sensor is installed correctly.

Q. Is the check result normal?

	Go to Step 3.

	Install the steering wheel sensor correctly (Refer to GROUP 35C - Steering Wheel Sensor ).

STEP 3. Service data check of the ASC-ECU.

Check the ASC-ECU service data with the following conditions (Refer to GROUP 35C - Troubleshooting

Item No.7: Steering angle

Check that the value of the service data deviates within ± 5° from the neutral position with the front wheel facing in the straight-ahead direction.
Turn the steering wheel fully to the left, and then turn it fully to the right. Then check that the value of the steering wheel sensor changes smoothly. In addition, check that the steering wheel angle on the service data almost matches the actual steering wheel angle.

Q. Are all the check results normal?

	Go to Step 4.

	Replace the steering wheel sensor (Refer to GROUP 35C - Steering Wheel Sensor ).

STEP 4. Service data check of the ASC-ECU.

Check again if the diagnosis code is set in the laser radar.

(1)Erase the set diagnosis code.

(2)Turn the ignition switch to the "LOCK" (OFF) position.

(3)Start the engine.

(4)Check if the diagnosis code is set.

Q. Is the diagnosis code set?

	Replace the laser radar (Refer to ).

	The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).