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DTC U0100 Engine CAN timeout
DTC U0121 ABS/ASC CAN timeout
DTC U0126 SAS CAN timeout
 
 
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
The EPS-ECU receives the signals from engine control module (ECM), ASC-ECU and steering wheel sensor through CAN communication.
 
 
 
FUNCTION
The signals from the ECM, ASC-ECU and steering wheel sensor are sent to the EPS-ECU for motor control.
 
 
 
TROUBLE JUDGMENT
Check Conditions
  • The power supply circuit system DTC (C1540, C1541) is not set.
  • The DTC related to engine circuit system, ASC circuit system and steering wheel sensor circuit system is not set.
Judgment Criterion
  • The signals from the ECM, ASC-ECU and steering wheel sensor are not sent, and the microcomputer determines that there is a problem in the system.
Fail Safe, Back Up Function
  • If DTC U0100 or U0121 is set, the ECU displays the electric power steering warning symbol to limit the power assistance.
  • If DTC U0126 is set, the feeling of steerage will be aggravated.
 
 
 
TROUBLESHOOTING HINTS
  • Malfunction of CAN bus line
  • Malfunction of the ECM
  • Malfunction of the ASC-ECU
  • Malfunction of the steering wheel sensor
  • Malfunction of the EPS-ECU
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), diagnose CAN bus line.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position 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) Use scan tool (M.U.T.-IIISE) 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) Engine start
(3) Check if the DTC is set.
Is DTCs No.U0100, U0121 or U0126 set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Using scan tool (M.U.T.-IIISE), check whether the DTC is set.
Use scan tool (M.U.T.-IIISE) to check if the same DTC (time-out) is set in the other ECU.
Is any DTC set?
: Replace the ECM (Refer to GROUP 13A - Engine control module ), and then go to Step 4.
: Replace the ASC-ECU (Refer to GROUP 35C - ASC-ECU ), and then go to Step 4.
: Replace the steering wheel sensor (Refer to GROUP 35C - Steering Wheel Sensor ), and then go to Step 4.
: Go to Step 4.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
(1) Erase the DTC.
(2) Engine start
(3) Check if the DTC is set.
Is DTCs No.U0100, U0121 or U0126 set?
Replace the EPS-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).