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ErrorLib — Industrial Fault Code Library

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b

Current Control Circuit Malfunction (ECM)

Fanuc · Alpha i Series AC Servo Motor and Spindle

What does b mean?

The circuit responsible for controlling the current within the ECM has malfunctioned. This is a critical internal fault affecting the ECM's ability to manage power flow.

Common Causes

  • Internal ECM fault in the current control circuit.
  • Wiring harness issue to the current sensor.
  • Failure of the current control module itself (ECM).

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect the control board of the ECM for visible damage or component failure.

  2. 2

    Check power supply rails to the current control circuit.

  3. 3

    Consult ECM diagnostics for specific sub-component failures.

Browse all codes in this manual (29)
Verified technical data. Last updated: April 2026

Related Faults

08Regeneration Excess Alarm1Over-current at Power Running (ECM)2Over-current at Regeneration (ECM)
Source: Fanuc Alpha i Series AC Servo Motor and Spindle
Open Manual (Page 588)Search more codes in this manual