Komatsu Fault Code
Free · no signupSPN 520830 FMI 02
Motor Stutters / Violent Shaft Vibration
System
Drive / Motor
Symptom
Motor Stutters / Violent Shaft Vibration
Diagnosis & fix steps
LOGIC: Traction Motor Resolver Angle Position Sensor Signal Drift.
ACTION: Inspect motor resolver multi-pin shielded pigtail connector. Check excitation coil resistance (~20–40Ω) and sine/cosine tracking outputs (~40–60Ω). Re-calibrate motor resolver zero-offset angle via OEM diagnostic software.
Red Seal field insights
Field Orientation: Permanent-magnet synchronous motors require microsecond rotor position tracking to rotate the stator magnetic field. A 5-degree resolver drift causes the inverter to fight rotor inertia, inducing massive torque ripple.
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