Yaskawa Error Code H66 May 2026

Some early firmware versions of the A1000 and V1000 had overly aggressive latch detection. Check Yaskawa’s website for firmware updates (contact local distributor with your drive model number).

If using vector control or servo positioning:

Perform a step response test using the drive’s software tool (DriveWizard or similar) to visualize overshoot.

To understand H66, you must understand the control method. In Closed Loop Vector control, the drive needs to know the exact rotor position to generate torque accurately. It relies on an encoder mounted on the non-drive end of the motor. yaskawa error code h66

When the drive commands the motor to move, it expects to see a return signal (pulses) from the encoder.

If you wish the drive to ignore the loss of the digital operator (e.g., in remote or permanently installed systems), check parameter:

Changing o2-04 to 1 allows operation without a keypad but will not fix an intermittent H66 caused by noise or hardware failure. Some early firmware versions of the A1000 and

Contact Yaskawa technical support if:

Yaskawa America, Inc. – Dride & Motion Division
Phone: 1-800-927-5292
Web: yaskawa.com

Document ID: YK-TB-H66-EN Rev. 1.0

Set L7-01 (Soft Stall Level) to 80–100% of motor rated current. This allows the drive to reduce speed gracefully instead of tripping on latch errors.

Yaskawa drives rely on precise motor parameters. If you performed rotational autotuning (T1-01 = 2 or 3) without the load properly decoupled, the drive’s inertia ratio (n8-55) or motor line-to-line resistance will be wrong. This causes overshoot.