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.

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Verified technical data. Last updated: March 2026

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Source: Fanuc Macro B CNC Programming