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DTC U0121: CAN time-out error (ABS/ASC)
 
 
 
 
DIAGNOSTIC FUNCTION
The TCM determines that the system is defective if the TCM can receive no CAN communication information from the ABS/ASC-ECU.
 
 
JUDGMENT CRITERIA
No information is received from the ABS/ASC-ECU for 0.5 seconds.
 
 
PROBABLE CAUSES
  • Malfunction of the CAN bus line
  • Malfunction of ABS/ASC-ECU
  • Malfunction of TCM
 
 
DIAGNOSIS
STEP 1. M.U.T.-III CAN bus diagnostics
Use scan tool to perform the CAN bus diagnosis.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Diagnosis, CAN Bus Diagnostics Table ).
 
STEP 2. M.U.T.-III diagnostic trouble code
Check if the ABS/ASC-related diagnostic trouble code is set.
Is the ABS/ASC-related diagnostic trouble code set?
Carry out the appropriate troubleshooting.
Go to Step 3.
 
STEP 3. M.U.T.-III diagnostic trouble code
Is diagnostic trouble code No. U0121 set in the other ECU, which communicates with the ABS/ASC-ECU via CAN?
Is the diagnostic trouble code set?
Go to Step 4.
Go to Step 5.
 
STEP 4. Symptom recheck after erasing diagnostic trouble code
Is the diagnostic trouble code set?
Replace ABS/ASC-ECU.
Intermittent malfunction.
 
STEP 5. Symptom recheck after erasing diagnostic trouble code
Is the diagnostic trouble code set?
Replace TCM.
Intermittent malfunction.