UL5

Mechanical Weakening Detection 2

Yaskawa · GA500 Maintenance and Troubleshooting

What does UL5 mean?

This error is generated when the drive detects an undertorque condition that satisfies the criteria for mechanical weakening, as configured by the L6-08 [Mechanical Fatigue Detect Select] parameter. This suggests potential wear, damage, or loosening of mechanical components within the system. Unresolved mechanical weakening can lead to catastrophic equipment failure.

Common Causes

  • Calculated motor current indicates excessive mechanical stress (P4-09).
  • Sudden surge in mechanical resistance.
  • Component failure in the driven machinery.
  • Drive detecting abnormal mechanical strain.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Conduct a detailed examination of the machine to identify any signs of mechanical deterioration, such as loose parts or wear.

  2. 2

    Replace or repair any components found to be deteriorating or damaged.

  3. 3

    Perform a Fault Reset to clear the error after necessary repairs are completed.

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Verified technical data. Last updated: March 2026

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Source: Yaskawa GA500 Maintenance and Troubleshooting