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Code No. U0401 Engine (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
Engine-related signals are sent or received to and from between ASC-ECU and engine control module via CAN bus lines.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
This diagnostic trouble code is set when the engine control module malfunction has been detected.
 
 
PROBABLE CAUSES
  • Malfunction of engine system
  • Malfunction of engine control module
  • Malfunction of ASC-ECU
  • Noise interference
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus lines.
Use the scan tool (M.U.T.-III) 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 repairing CAN bus lines
Is diagnostic trouble code No. U0401 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 U0401 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. se scan tool (M.U.T.-III) to confirm a diagnostic trouble code of other systems.
Check if the diagnostic trouble code is set in the engine control module (Refer to GROUP 13A, Diagnostic Trouble Code Chart ).
Is the diagnostic trouble code set?
Troubleshoot the engine control module diagnostic trouble code. 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. U0401 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 ).