Fanuc 414 Servo Alarm Z Axis Detect Error Guide
Unlike X and Y axes, the Z-axis is vertical. Gravity is an implicit load. If you have a vertical mill, the Z-axis brake is engaged to hold the spindle head up when the servo is off. A 414 alarm usually precedes a Z-axis drop. When the servo shuts off, the brake must hold. If the brake is worn, the head can crash into the table or part. Never ignore this alarm without first blocking the Z-axis (place a block of wood or a jack under the spindle head).
The CNC uses a dual-check method to confirm encoder feedback:
This alarm is not about motor overload or overcurrent. It is strictly about loss of position feedback. fanuc 414 servo alarm z axis detect error
Start here before using meters or oscilloscopes:
Check battery voltage (if absolute encoder): Unlike X and Y axes, the Z-axis is vertical
Visually inspect encoder cable from Z-motor to servo amp:
Reseat connectors at:
Swap axes temporarily (if possible):
A floating ground between the CNC and the transformer creates a voltage potential. The 5V encoder signal sees 2V of AC noise superimposed. This corrupts the feedback, triggering a detect error. The CNC uses a dual-check method to confirm