Code No. C1657 Implausible coding data


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 (Refer to GROUP 54C, CAN Bus Diagnostics Table).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION

    EPS-ECU receives variant coding data from the ETACS-ECU.

FUNCTION

    The coding data is sent to the EPS-ECU for motor control.

TROUBLE JUDGEMENT
Check Conditions
  • The power supply circuit system diagnosis code (No. C1540, C1541) is not set.
  • The ETACS circuit system diagnosis code is not set.
Judgement Criterion
  • The coding data from the ETACS-ECU are not matched twice consecutively.
  • The abnormal coding data is sent from the ETACS-ECU, and the microcomputer determines that there is a problem in the system.
Fail Safe, Back Up Function
    The EPS-ECU stores diagnosis code No. C1657.

PROBABLE CAUSES

  • Malfunction of CAN bus line
  • Malfunction of the EPS-ECU
  • Malfunction of the ETACS-ECU

DIAGNOSIS PROCEDURE

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 3
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2

STEP 2. Diagnosis code recheck after resetting CAN bus lines
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis codes C1657 set?
Go to Step 3
This diagnosis is complete.

STEP 3. M.U.T.-III other system diagnosis code
Use M.U.T.-III to check whether the ETACS-ECU-related or engine ECU-related diagnosis code is set or not.

Q. Is any diagnosis code set?
Troubleshoot for the relevant diagnosis code.
Go to Step 4

STEP 4. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis codes C1657 set?
Replace the EPS-ECU (Refer to ). Then go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .

STEP 5. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis codes C1657 set?
Return to Step 1.
This diagnosis is complete.