FANUC Alarm List PDF Download & 20+Common Drive Alarms

Download the FANUC Alarm List PDF at the end of this article.

Table of Contents

Introduction

FANUC drive alarms play a crucial role in keeping CNC systems running smoothly. They act as important indicators that help operators and technicians pinpoint potential issues. By understanding these alarm codes, you can significantly decrease machine downtime and potentially save on costly repairs.

In our previous article, we explored the different categories of FANUC alarm codes. This time, we’ll dive into the common causes of FANUC drive alarms and offer practical solutions. We also have a handy downloadable PDF that lists these alarms to support your troubleshooting efforts.

Overview of FANUC Drive Alarms

FANUC drives are essential components in CNC machines, enabling precise control of the motors that power them. However, when drive alarms occur, it can be a real concern for those operating the machinery. These alarms may arise due to various reasons, such as electrical issues, overheating, overcurrent, or even problems with the encoders. It’s important to take the time to diagnose these alarms properly, as doing so is key to keeping everything running smoothly and efficiently.

Common Causes of FANUC Drive Alarms

  • Overcurrent or overload conditions
  • Voltage fluctuations
  • Overheating due to inadequate cooling
  • Encoder communication failures
  • Faulty wiring or hardware malfunctions
FANUC Drive in lathe, fanuc alarm list pdf

1. Overcurrent/Overload Alarms

n = axis number, e.g. 1, 2, 3, etc.

  • 4n00 : IPM detected overcurrent
    • Cause: Motor short circuit, drive module failure, damaged cables.
    • Solution: Inspect motor cables, replace the drive module if needed.
  • 4n01: Motor current abnormal
    • Cause: Motor overload, incorrect parameter settings, drive failure.
    • Solution: Reduce mechanical load, adjust acceleration/deceleration settings.

2. Voltage Abnormalities

  • 4n30: DC link overvoltage
    • Cause: High input voltage, regenerative resistor failure.
    • Solution: Check input voltage, replace regenerative resistor.
  • 4n31: DC link undervoltage
    • Cause: Low power supply voltage, power module failure.
    • Solution: Verify power input, replace power module if necessary.
FANUC Alarm in controller Screen

3. Overheating Alarms

  • 4n04: Drive heat sink overheating
    • Cause: Poor ventilation, cooling fan failure, high ambient temperature.
    • Solution: Clean heat sinks, check fan operation.
  • 4n05: Motor overheating
    • Cause: Excessive load, insufficient cooling.
    • Solution: Reduce machine load, ensure proper motor cooling.

4. Encoder/Feedback Alarms

  • 4n40: Encoder communication error
    • Cause: Disconnected encoder cables, loose connectors.
    • Solution: Inspect encoder wiring, secure connections.
  • 4n41: Encoder battery low (absolute encoder)
    • Cause: Depleted battery.
    • Solution: Replace battery, reset reference position.
  • 4n44: Encoder pulse error
    • Cause: Contamination, signal interference.
    • Solution: Clean encoder, shield cables against interference.
FANUC Alarm with a hand

5. Hardware Detection Failures

  • 4n50: Drive current detection error
    • Cause: Current sensor failure, internal circuit damage.
    • Solution: Replace drive module.
  • 4n55: Heat sink temperature sensor failure
    • Cause: Sensor wiring fault or damage.
    • Solution: Check sensor connections, replace if necessary.

6. Other Common Alarms

  • 4n70: CNC-Drive communication failure
    • Cause: Optical cable connection issue, power failure.
    • Solution: Check fiber optic cables, ensure power is supplied.
  • 4n90: Software parameter mismatch
    • Cause: Incorrect drive parameter settings.
    • Solution: Reconfigure drive parameters, restore backup settings.

FANUC Servo Alarm Codes

  • SV0301: APC alarm – Communication error
    • Cause: Poor feedback line connection or servo drive control board issue.
    • Solution: Check feedback cables and replace control board if needed.
  • SV0306: APC alarm – Overflow alarm
    • Cause: Related to parameters No.2084, No.2085 settings.
    • Solution: Adjust parameters accordingly.
  • SV0307: APC alarm – Excess axis movement
    • Cause: Possible feedback line issue.
    • Solution: Inspect feedback cable and connection.
  • SV0360: Pulse encoder code check error (built-in)
    • Cause: Possible issue with the pulse encoder.
    • Solution: Check and replace encoder if necessary.
  • SV0364: Soft phase alarm (built-in)
    • Cause: Related to encoder performance or poor feedback cable shielding.
    • Solution: Improve shielding and check encoder functionality.
  • SV0366: Pulse loss (built-in)
    • Cause: Poor feedback cable shielding or interference.
    • Solution: Shield cable and minimize interference.
  • SV0367: Count loss (built-in)
    • Cause: Similar to SV0366, could be feedback line issues or encoder failure.
    • Solution: Inspect cables and encoder.
  • SV0368: Serial data error (built-in)
    • Cause: Poor shielding in feedback cables.
    • Solution: Improve cable shielding.
  • SV0369: Serial data transmission error (built-in)
    • Cause: Transmission issues in serial data.
    • Solution: Check transmission lines and connections.
  • SV0380: External LED error in separate-type detector
    • Cause: Possible problem in external interface unit (SDU).
    • Solution: Inspect and replace SDU if necessary.
  • SV0385: Serial data error (external)
    • Cause: Communication issue in external interface.
    • Solution: Check external data connections.

FANUC Spindle Alarm List

  • 400/402/406/490: Overload alarm.
    • Cause: Overheating of spindle motor or amplifier.
  • 411: Spindle speed deviation error.
    • Cause: Large difference between actual and commanded speed.
  • 434: Spindle orientation timeout.
    • Cause: Spindle fails to reach designated position in time.
FANUC Alarm in controller Screen

How to Troubleshoot FANUC Drive Alarms?

Step 1: Initial Inspection

  • Check the power supply and confirm drive status.
  • Note down alarm codes and verify against the FANUC drive alarm list.

Step 2: Detailed Diagnosis

  • Measure voltage levels and inspect signals.
  • Review drive parameters and logs.

Step 3: Repair or Replacement

  • If damage is detected, replace the faulty drive components.
  • Inspect cooling systems and connections.

Step 4: System Testing

  • Clear alarm history and reset the system.
  • Run test cycles to ensure stable operation.

Preventing FANUC Drive Alarms

  • Regular drive maintenance and cooling system checks.
  • Ensuring stable power supply and proper grounding.
  • Routine inspections of cables and connectors.
  • Keeping drive firmware and parameters up to date.

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FANUC Alarm List PDF Download

For easy access to all the alarm codes and troubleshooting steps, download our FANUC Alarm List PDF.

FANUC Alarm List PDF

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FAQ

What is a FANUC alarm list?

A FANUC alarm list is a reference guide that explains CNC alarm codes, their causes, and recommended troubleshooting steps. It helps technicians quickly identify machine issues such as servo errors, spindle overloads, or drive faults.

You can download the FANUC Alarm List PDF at the end of this article. The document contains a structured list of alarms including drive alarms, servo alarms, and spindle alarms for easier troubleshooting.

Some of the most common FANUC drive alarms include:

  • 4n00 – Overcurrent detected by IPM
  • 4n01 – Motor current abnormal
  • 4n30 – DC link overvoltage
  • 4n31 – DC link undervoltage
  • 4n04 – Drive heat sink overheating

These alarms are usually related to power supply issues, motor overload, cooling problems, or cable damage.

FANUC servo alarms are usually triggered by problems in the feedback system or servo parameters. Common causes include:

  • Encoder communication errors
  • Poor feedback cable connections
  • Incorrect servo parameter settings
  • Electrical interference

Examples include SV0301 APC communication error and SV0366 pulse loss alarm.

Typical FANUC spindle alarms include:

  • 400 / 402 / 406 / 490 – Spindle overload
  • 411 – Spindle speed abnormal
  • 434 – Spindle orientation timeout

These alarms usually occur due to excessive load, overheating, or spindle control issues.

You can reduce the occurrence of FANUC drive alarms by:

  • Regularly checking motor cables and connectors
  • Keeping drive cooling systems clean
  • Ensuring stable power supply
  • Performing routine CNC maintenance
  • Using proper shielding for encoder cables

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Get in touch with us and provide as much detail as possible about the issue you are experiencing.

Our professional repair team will help assess the severity of the problem and the possibility of repair.

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The customer sends or delivers the servo drive to our company. We register it in our system and prepare it for further inspection.

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