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DTC C1803 ACC Mode Off Disagreement
DTC C1804 ACC Deactivation Disagreement
 
 
cautionBefore replacing the ECU, ensure that the communication circuit is normal.
 
 
OPERATION
The ASC-ECU receives ACC/FCM control status signal from the ACC/FCM-ECU, and vehicle control status signal from the ECM via CAN bus lines, respectively.
 
 
 
DTC SET CONDITIONS
If the information received from the ACC/FCM-ECU does not correspond to that received from the ECM, the ASC-ECU will set the Diagnostic Trouble code.
 
 
 
PROBABLE CAUSES
  • CAN bus lines are abnormal (External noise interference)
  • ECM malfunction
  • ACC/FCM-ECU malfunction
  • ASC-ECU malfunction
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line.
Use scan tool (M.U.T.-IIISE) to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
 
STEP 2. Using scan tool (M.U.T.-IIISE), check other DTC.
Use scan tool (M.U.T.-IIISE) to check that any DTC other than DTC C1803 or C1804 is set in ASC-ECU.
Is the DTC set?
Troubleshoot for the relevant DTC (Refer to ).
Go to Step 3.
 
STEP 3. Using scan tool (M.U.T.-IIISE), check other system DTC.
Use scan tool (M.U.T.-IIISE) to check whether any coding-related DTC is set by ECM (Refer to GROUP 13A - Troubleshooting/Diagnostic Trouble code chart ) or ACC/FCM-ECU (Refer to GROUP 17 - ACC/FCM-ECU/Diagnostic Trouble code chart ).
Is the DTC set?
Troubleshoot for the relevant DTC.
Go to Step 4.
 
STEP 4. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Turn the ignition switch to the "ON" position.
Is DTC C1803 or C1804 set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).