Code No. U0401: Engine
(CAN message)
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- If there is any
problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis,
diagnose the CAN bus lines (Refer to GROUP 54C -
CAN Bus Diagnostics Table
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- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out
the calibration of the G and yaw rate sensor and the steering wheel sensor (Refer to and ).
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OPERATION
Engine-related signals are sent or received to and from between ASC-ECU and engine ECU
via CAN bus lines.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when the engine-ECU malfunction has been detected.
PROBABLE CAUSES
- Malfunction of engine system
- Malfunction of engine-ECU
- Malfunction of the hydraulic unit assembly (integrated with ASC-ECU)
- Noise interference
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STEP 1. M.U.T.-III CAN bus diagnosis.
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Use the M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 3.
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 Repair the CAN bus line. (Refer to GROUP 54C -
Troubleshooting ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines.
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Q.
Is diagnosis code No. U0401 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Check for diagnosis codes of other systems.
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Check if diagnosis code(s) other than U0401 is set.
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Q.
Is the diagnosis code set?
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Follow the relevant diagnosis code procedure, and then go to Step 6.
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Go to Step 4.
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STEP 4. Use M.U.T.-III to confirm a diagnosis code of other systems.
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Check if the diagnosis code is set in the engine-ECU.
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Q.
Is the diagnosis code set?
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Troubleshoot the engine-ECU diagnosis code (Refer to GROUP 13A -
Diagnosis
Code Chart ). Then go to Step 6.
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Go to Step 5.
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STEP 5. Diagnosis code recheck.
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Check again if the diagnosis code is set.
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(1)Erase the set diagnosis code.
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(2)Ignition switch: "LOCK" (OFF)
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Q.
Is diagnosis code No. U0401 set?
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Replace the hydraulic unit assembly (integrated with ASC-ECU) (Refer to ).
Then go to Step 6.
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The trouble can be an intermittent malfunction (Refer to GROUP 00 -
How
to Cope with Intermittent Malfunction).
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STEP 6. Diagnosis code recheck.
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Check again if the diagnosis code is set.
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(1)Erase the set diagnosis code.
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(2)Ignition switch: "LOCK" (OFF)
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Q.
Is diagnosis code No. U0401 set?
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Return to Step 3.
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This diagnosis is complete.
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