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DTC C1781 SAS internal fail
 
 
caution
  • 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 GROUP 35C - On-vehicle Service ).
 
 
OPERATION
FCM/LDW/AHB-ECU communicates with the steering wheel sensor via the CAN bus lines.
 
 
DIAGNOSTIC FUNCTION AND TROUBLE JUDGMENT
This DTC is set when the abnormality below is detected:
  • The ECU receives a signal which indicates an internal error in the steering wheel sensor.
 
 
TROUBLESHOOTING HINTS
  • The steering wheel sensor has not been calibrated correctly.
  • Malfunction of the steering wheel sensor (column switch assembly)
  • Malfunction of the FCM/LDW/AHB-ECU
 
 
DIAGNOSIS
STEP 1. Check whether the steering wheel sensor is installed properly.
Is the check result normal?
Go to Step 2.
Install the steering wheel sensor properly.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check data list.
Check the FCM/LDW/AHB-ECU data list (Refer to ).
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect Scan Tool (M.U.T.-IIISE) ."
(2) Check the input signal from the steering wheel sensor.
  • Vehicle stopped (the steering wheel is in the neutral position)
 
Item No.Item nameNormal condition
17Steering wheel angle-6 to 6 deg
  • Vehicle is running.
 
Item No.Item nameNormal condition
17Steering wheel angleNearly the same as the steering wheel operation angle (-750 to 750 deg)
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 3.
Replace the steering wheel sensor (column switch assembly) (Refer to ).
 
STEP 3. Using scan tool (M.U.T.-IIISE), read the DTC again.
Check again if the DTC is set in the FCM/LDW/AHB-ECU.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) Check if DTC is set.
Is the DTC set?
Replace the FCM/LDW/AHB-ECU (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 ).