The diagnostic registers provide the specific fault bit that triggered the alarm. For Z-axis faults, the relevant registers are:
It should always be your first step before calling a FANUC service technician who will charge $500 just to walk in the door.
To move beyond the general 414 error, you must check the diagnostic parameters on your Fanuc control: fanuc 414 servo alarm z axis detect error repack
If the servo alarm triggers on X or Y, the axis stops. If the servo alarm triggers on Z, the head or spindle assembly (weighing hundreds of pounds) will unless a brake is engaged.
A on the Z-axis indicates a high-current detection error . This means the CNC has detected an abnormal amount of current flowing through the servo amplifier or motor for that specific axis. The diagnostic registers provide the specific fault bit
| Bit | Bit Name | Description | LED Indication | |-----|----------|-------------|----------------| | #7 (bit 7) | OVL | Overload alarm | Servo amplifier LED | | | LV | Low voltage alarm → LED [2] or [3] lights | | #5 (bit 5) | OVC | Overcurrent alarm (software detection) | | #4 (bit 4) | HCA | Abnormal current alarm → LED [8] lights | | #3 (bit 3) | HVA | Overvoltage alarm → LED [1] lights | | #2 (bit 2) | DCA | Discharge (regenerative) alarm → LED [4] or [5] lights | | #1 (bit 1) | FBA | Disconnection (feedback) alarm | | #0 (bit 0) | OFA | Overflow alarm |
If the troubleshooting steps above do not resolve the issue, it may be necessary to repack the servo motor. Repacking involves disassembling the motor, cleaning and inspecting its components, and reassembling it with new bearings, seals, and lubricant. If the servo alarm triggers on Z, the
At this point, many shops would call for a ballscrew replacement ($5k–$10k + weeks of lead time). But there is a : Repacking .
Do you have the from No. 200 or 204, or can you confirm if the alarm clears when the motor cables are disconnected? Diagnose a Fanuc High Current Alarm in 10-Steps
While many 414 alarms can be resolved through systematic troubleshooting, certain conditions require professional intervention: