The alarm is almost always related to hardware or environmental interference rather than programming errors. Primary triggers include:
Dirt, oil, or coolant ingress into the pulse coder or scale. fanuc 366 alarm
Inspect the feedback cable between the servo motor and the amplifier for fraying, sharp bends, or loose plugs. Reseat the connectors to ensure a solid connection. The alarm is almost always related to hardware
Some "pulse mismatch" errors can be cleared by navigating to the system menu and performing a pulse coder reset . fanuc 366 alarm
External electromagnetic interference disrupting the high-precision pulse signal. Troubleshooting and Resolution Steps
If your CNC control displays a 366 alarm, follow these steps to isolate and fix the issue: