Trouble symptom
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Inspection procedure
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Reference pages or actions
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The M.U.T.-III cannot communicate with the electric
power steering system.
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1 <CAN communication system check>
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2 <ECU power supply circuit system check>
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Electric power steering system warning lamp illuminates but diagnosis
code is not stored.
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3
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The steering has become heavy, but the electric power steering warning
lamp does not illuminate (This is normal, because the electric power steering is limiting assist operation).
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If the vehicle is driven under heavy load (e.g. consecutively turning the steering to
full lock or severe cornering), the electric power steering motor drive circuit will become
hot. In this case, the electric power steering system will limit assist operation by decreasing
the motor current to avoid damage. In this case, the steering will become heavy, but the electric
power steering warning lamp does not illuminate. If the circuit temperature reduces after a
while, the assist operation will return to the normal level.
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Reproduce the steering operation, which your customer did. Check
the M.U.T.-III data list item No.07 (assist limit current), and confirm that the electric power
steering system limited the assist operation (Refer to ). Note
that this is not a failure.
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When the ignition switch is turned on, the system does not perform
the bulb check for the electric power steering warning lamp (The electric power steering warning
lamp does not illuminate until the engine is started).
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The ignition switch is turned to the "ON" position (within approximately 0.3 second) again
immediately after it is turned to the "LOCK" (OFF) position, the electric power steering warning
lamp does not illuminate.
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Replace the combination meter assembly (Refer to GROUP 54A, Combination
Meter ).
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