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DTC U0121: ABS/ASC 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.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
  • The power supply mode of electric motor switch is ON.
  • The PHEV-ECU power supply voltage is between 10 and 16.5 volts.
Judgment Criterion
  • The PHEV-ECU sets DTC U0121 when it cannot communicate with the ASC-ECU via CAN correctly.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
 
 
PROBABLE CAUSES
  • Malfunction of CAN bus line.
  • Malfunction of the PHEV-ECU.
  • The power supply to the ASC-ECU fails.
  • Malfunction of the ASC-ECU.
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), diagnose CAN bus line.
Use the scan tool (M.U.T.-IIISE) to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 5.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set.
Check whether the ASC-ECU related DTC is set (Refer to GROUP 35C - Diagnostic Trouble Code Chart ).
Is the DTC set?
Troubleshoot for the relevant DTC.
Go to Step 3.
 
STEP 3. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set.
Check if DTC U0121 is set in the other system (Refer to GROUP 54C - CAN Communication-related DTC (U-Code) Table ).
Is the DTC set?
Troubleshoot for the relevant DTC.
Go to Step 4.
 
STEP 4. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(2) Check if the DTC is set.
Is the DTC set?
Replace the PHEV-ECU (Refer to ). Then go to Step 5.
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 5 Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(2) Check if the DTC is set.
Is the DTC set?
Retry the troubleshooting.
The procedure is complete.