[Previous][Next]
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
  • Electric power steering-ECU receives variant coding data from the ETACS-ECU.
 
 
 
FUNCTION
  • The coding data is sent to the electric power steering-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 electric power steering-ECU set DTC No. C1657.
 
 
 
PROBABLE CAUSES
  • Malfunction of CAN bus line
  • Malfunction of the electric power steering-ECU
  • Malfunction of the ETACS-ECU
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.
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 the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3) Check if the DTC is set.
Is DTC C1657 set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Using scan tool MB991958 other system DTC
Use scan tool to check whether the ETACS-ECU-related DTC is set or not.
Is any 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 from the "LOCK" (OFF) position to the "ON" position.
(3) Check if the DTC is set.
Is DTC C1657 set?
Replace the electric power steering-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 DTC is set again.
(1) Erase the DTC.
(2) Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3) Check if the DTC is set.
Is DTC C1657 set?
Return to Step 1.
This diagnosis is complete.