Fanuc SV 400 4th: Fanuc 0i Error Code SV 400 4th

Symptoms

The servo control unit has detected a system-level alarm. The servo motor may stop, and the axis may lose position. Alarm SV 400 is displayed for the 4th axis.

Possible Causes

4th axis servo amplifier fault or overload
4th axis servo motor cable damaged or disconnected
4th axis mechanical binding or excessive load
Servo parameter setting incorrect for this axis

Troubleshooting Steps

Step 1: Check the 4th axis servo amplifier status LEDs for alarm indication
Amplifier status LED shows alarm code if amplifier fault
Step 2: Inspect 4th axis servo motor cable and connectors for damage
Cable intact, connectors properly seated
Step 3: Check 4th axis mechanical system for binding or excessive load
Axis moves freely without excessive force when motor is de-energized
Step 4: Verify servo parameters for 4th axis match motor and amplifier specifications
Parameters match the motor/amplifier data sheet
Step 5: Clear alarm and test axis movement at low speed
Axis moves smoothly without alarm returning

How to Reset

Power off the machine, correct the fault, power on, and press RESET. For servo alarms, always investigate the root cause before restarting to prevent damage.

Common Replacement Parts

varies: 4th axis servo amplifier or motor (if confirmed faulty) (Confirm with FANUC servo system test before replacement)

Frequently Asked Questions

Q: What does Fanuc SV 400 4th alarm mean?
Servo System Alarm: The servo control unit has detected a system-level alarm. The servo motor may stop, and the axis may lose position. This alarm is specific to the 4th axis.
Q: How do I clear Fanuc SV 400 alarm?
Power off the machine, investigate the servo amplifier status, check motor cables and mechanical system, then power on and clear the alarm with RESET.

Fanuc 0i Error Code SV 400 4th