303
Serial Pulse Coder LED Disconnection (LDAL)
Fanuc · αi series AC Servo Motor
What does 303 mean?
An LED disconnection (LDAL) was detected within the serial pulse coder. This indicates an internal failure of the pulse coder's light-emitting diode, essential for its operation.
Common Causes
- Internal LED disconnection within the serial pulse coder.
Repair Steps
- 1
Turn the main power OFF.
- 2
If this alarm recurs immediately when power is reapplied, replace the motor (which contains the pulse coder).
Verified technical data. Last updated: March 2026
Source: Fanuc αi series AC Servo Motor