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Code No. U0402 T/M (CAN message)
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, CAN Bus Diagnostics Table ).
  • Before replacing the ECU, ensure that the communication circuit is normal.
  • When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to and ).
 
 
OPERATION
CVT-related signals are sent or received between the ASC-ECU and the CVT-ECU via CAN bus lines.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
This diagnostic trouble code is set when the CVT-ECU malfunction has been detected.
 
 
PROBABLE CAUSES
  • CVT-related malfunction
  • The CVT-ECU is defective.
  • Malfunction of ASC-ECU
  • Noise interference
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use the scan tool MB991958 to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus line (Refer to GROUP 54C, Troubleshooting ). On completion, go to Step 2.
 
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Is diagnostic trouble code No. U0402 set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Check for diagnostic trouble codes of other systems.
Check if diagnostic trouble code(s) other than U0402 is set.
Is the diagnostic trouble code set?
Follow the relevant diagnostic trouble code procedure, and then go to Step 5.
Go to Step 4.
 
STEP 4. Use scan tool MB991958 to confirm a diagnostic trouble code of other systems.
Check if the diagnostic trouble code is set in the CVT-ECU (Refer to GROUP 23A, Diagnostic Trouble Code Chart ).
Is the diagnostic trouble code set?
Follow the relevant diagnostic trouble code procedure. Then go to Step 5.
Go to Step 5.
 
STEP 5. Diagnostic trouble code recheck
Check again if the diagnostic trouble code is set.
(1) Erase the set diagnostic trouble code.
(2) Ignition switch: "LOCK" (OFF)
(3) Ignition switch: "ON"
Is diagnostic trouble code No. U0402 set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).