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ErrorLib — Industrial Fault Code Library

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4

Over-current of Discharge Current (ECM)

Fanuc · Macro B CNC Programming

What does 4 mean?

An over-current occurred in the discharge current from the Energy Charge Module's (ECM) Capacitor Modules. This suggests an issue with the energy being released, possibly due to a fault in the ECM's discharge circuit, the Resistor Module (A06B-6158-H030), or an external short circuit drawing excessive power.

Common Causes

  • The discharge current exceeds its maximum allowed limit.
  • Short circuit in the discharge path.
  • Faulty discharge components leading to high current draw.
  • Overload condition during discharge cycle.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Immediately stop the machine using the emergency stop button and open the external Main Circuit Contactor (MCC) of the Power supply.

  2. 2

    Inspect the wiring of the discharge circuit between the ECM Control Module and the Resistor Module for any short circuits or damage.

  3. 3

    Verify the integrity of the Resistor Module (A06B-6158-H030), ensuring its resistance (expected 30 ohm, page 578) is within specification and it shows no signs of overheating.

  4. 4

    Check the Capacitor Modules (A06B-6158-H020) for internal faults that could cause uncontrolled discharge.

  5. 5

    Ensure that the external load connected to the ECM is not drawing excessive current during discharge operations, which could trigger this alarm.

Browse all codes in this manual (26)
Verified technical data. Last updated: April 2026

Related Faults

08Regeneration Excess Alarm1Over-current at Power Running (ECM)2Over-current at Regeneration (ECM)
Source: Fanuc Macro B CNC Programming
Open Manual (Page 588)Search more codes in this manual