[ Model - ECLIPSE CROSS / Year - 2018 ]
2018 / ECLIPSE CROSS / EC - Workshop Manual
52 -INTERIOR AND SUPPLEMENTAL RESTRAINT SYSTEM(SRS) > 52B-SUPPLEMENTAL RESTRAINT SYSTEM (SRS) > TROUBLESHOOTING > DIAGNOSIS CODE PROCEDURES > DTC U0121 ABS/ASC CAN timeout/Not equipped
Code No. U0121: ASC CAN timeout
 
 
caution
  • If the diagnosis code No. U0121 is set, diagnose the CAN bus lines.
  • When replacing the ECU, always check that the SRS circuit is normal.
 
 
FUNCTION
If signal from the ASC-ECU cannot be received, the SRS-ECU sets the diagnosis code No. U0121.
 
 
TROUBLE JUDGEMENT
Because of the CAN-C bus circuit malfunction, if SRS-ECU becomes unable to perform the normal data transmission, SRS-ECU determines that an abnormality is present.
cautionIn order to record the diagnosis code even after diagnosis code recording is stopped, erase the past failure if there is the record of a past failure after implementing troubleshooting.
 
 
PROBABLE CAUSES
  • Malfunction of CAN bus line
  • Malfunction of ASC-ECU
  • Malfunction of SRS-ECU
 
 
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-IIISE CAN bus diagnostics
Use the M.U.T.-IIISE to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
 
STEP 2. Check the M.U.T.-IIISE Diagnosis code for other systems
Check that the ASC-ECU set a diagnosis code.
Is the diagnosis code set?
Diagnose the ASC-ECU (Refer to GROUP 35C - Troubleshooting ).
Go to Step 3.
 
STEP 3. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the SRS-ECU.
(1) Erase the diagnosis code.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) On completion, check that the diagnosis code is set again.
Is the diagnosis code set?
Replace the ASC-ECU (Refer to GROUP 35C - Hydraulic unit ). After replacing the ECU, carry out the CAN bus diagnostics. Then go to Step 4 .
A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the ASC-ECU and the SRS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
 
STEP 4. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the SRS-ECU.
(1) Erase the diagnosis code.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) On completion, check that the diagnosis code is not set again.
Is the diagnosis code set?
Replace the SRS-ECU (Refer to ). After replacing the ECU, carry out the CAN bus diagnostics.
A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the ASC-ECU and the SRS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).