Code No.C1785: Fault Detection 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 communication circuit is normal.
- When the diagnosis code No.C1785 is set in FCM-ECU, the diagnosis code may also be set in ETACS-ECU. When the diagnosis code is set in ETACS-ECU, perform the diagnosis of the diagnosis code for ETACS-ECU first.
- When the FCM-ECU is replaced, calibrate the radar (refer to
 ).
|
OPERATION
FCM-ECU receives the vehicle information stored in ETACS-ECU via CAN bus lines.
DIAGNOSIS CODE SET CONDITION
This diagnosis code is set when the abnormality below is detected:
- The malfunction detection control signal, which is sent from the ETACS-ECU, cannot be received for a certain period.
PROBABLE CAUSES
- The CAN bus line is defective.
- Malfunction of the ETACS-ECU
- Malfunction of the FCM-ECU
|
|
STEP 1. M.U.T.-III CAN bus diagnostics.
|
|
|
Use M.U.T.-III to diagnose the CAN bus lines.
|
|
|
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 if the diagnosis code is set in the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ).
|
|
|
Q.
Is the diagnosis code set?
|
|
|
Troubleshoot the ETACS-ECU diagnosis code (Refer to GROUP 54A - ETACS-ECU ).
|
|
|
|
|
|
Go to Step 3.
|
|
|
|
|
|
STEP 3. Check whether the diagnosis code is set again.
|
|
|
Check again if the diagnosis code is set in the FCM-ECU.
|
|
|
(1)Erase the diagnosis code.
|
|
|
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
|
|
|
(4)On completion, check that the diagnosis code is set again.
|
|
|
Q.
Is diagnosis code No. C1785 set?
|
|
|
Replace the FCM-ECU (Refer to ).
|
|
|
|
|
|
Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
|
|
|
|