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DTC C1657 Implausible coding data
 
 
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 (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 JUDGMENT
Check Conditions
  • The power supply circuit system DTC (No. C1540, C1541) is not set.
  • The ETACS circuit system DTC is not set.
Judgment 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 sets DTC No. C1657.
 
 
 
TROUBLESHOOTING HINTS
  • Malfunction of CAN bus line
  • Malfunction of the EPS-ECU
  • Malfunction of the ETACS-ECU
 
 
 
 
DIAGNOSIS
STEP 1. Scan tool (M.U.T.-IIISE) CAN bus diagnostics.
(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.
(4) Turn off the power supply mode of the electric motor switch.
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. DTC recheck after resetting CAN bus lines.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check if the DTC is set.
Is DTC C1657 set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Scan tool (M.U.T.-IIISE) other system DTC.
Check if DTC is set in the ETACS-ECU.
Is any DTC set?
Troubleshoot the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU, Troubleshooting ).
Go to Step 4.
 
STEP 4. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check if the DTC is set.
Is DTC C1657 set?
Replace the EPS-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).