If the encoder is physically damaged, filled with oil, or has a dead internal LED, it will need to be replaced. For some FANUC motors, the pulse coder can be replaced as an individual unit.
Even if it looks fine, replace the cable as a cheap and fast diagnostic step.
On many FANUC models, the pulse coder can be unbolted and replaced independently of the entire motor. fanuc 366 alarm
If you'd like to narrow down the issue further, let me know:
If slight moisture is detected, cleaning the encoder board with specialized electronic cleaner and drying it gently with compressed air or a heat gun can sometimes revive the MCU. Ensure the housing gasket is replaced upon reassembly. If the encoder is physically damaged, filled with
Fanuc SV0366 Alarm indicates an overheat or abnormal temperature
While the alarm points directly to the pulse coder hardware, external variables frequently trigger this failure. 1. Internal Pulse Coder Component Failure On many FANUC models, the pulse coder can
Swap the feedback cables at the servo amplifier end. If the alarm moves to the other axis on the screen, the cable or amplifier port is bad. If the alarm stays on the original axis, the problem is down at the motor/encoder.
Disconnect the encoder cable from both the motor end and the servo amplifier end. Inspect the pins for bent components, rust, or moisture.