Code No. C1778: Vehicle Speed Signal Failure



caution
  • 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.
  • Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION


ACC/FCM-ECU communicates with the ASC-ECU via the CAN bus lines.

DIAGNOSIS CODE SET CONDITION


This diagnosis code is set when the abnormality below is detected:


PROBABLE CAUSES




DIAGNOSIS PROCEDURE


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


Use M.U.T.-III to perform the CAN bus diagnosis.

Q. Is the check result normal?

Go to Step 2
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ).

STEP 2. M.U.T.-III other system diagnosis code.


Check the ASC diagnosis code (Refer to GROUP 35C - Troubleshooting ).

Q. Is the diagnosis code set?

Perform the relevant troubleshooting.
Go to Step 3

STEP 3. Check whether the diagnosis code is reset.


Q. Is diagnosis code No.C1778 set?

Replace the hydraulic unit (integrated with ASC-ECU) (Refer to GROUP 35C - Hydraulic Unit ). Then go to Step 4
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 4. Check whether the diagnosis code is reset.


Q. Is diagnosis code No.C1778 set?

Replace the ACC/FCM-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).