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DTC C1777: System Fail Detected (ASC)
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC 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.
 
 
OPERATION
ACC-ECU communicates with the ASC-ECU via the CAN bus lines.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITION
This DTC is set when the abnormality below is detected:
  • A signal, which indicates a defective ASC system, is received from the ASC-ECU.
 
 
PROBABLE CAUSES
  • Malfunction of the CAN bus line
  • Malfunction of the ASC-ECU
  • Malfunction of ACC-ECU

 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), diagnose CAN bus line.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Turn on the power supply mode of the electric motor switch.
(3) Diagnose the CAN bus line. [Refer to GROUP 54C - Explanation About The Scan Tool (M.U.T.-IIISE) Can Bus Diagnostics ]
(4) Turn off the power supply mode of the electric motor switch.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Diagnosis, Can Bus Diagnostics Table ).
 
STEP 2. Using scan tool (M.U.T.-IIISE), check ASC system DTC.
Check the ASC DTC (Refer to GROUP 35C - Diagnosis <ASC-ECU> ).
Is the DTC set?
Perform the relevant diagnosis.
Go to Step 3.
 
STEP 3. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Is DTC C1777 set?
Replace the ACC-ECU (Refer to ).
It can be assumed that this malfunction is intermittent (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunction ).