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ErrorLib — Industrial Fault Code Library

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303

Serial Pulse Coder LED Disconnection (LDAL)

Fanuc · Alpha i 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 & Checklist

Click steps to track your progress.

  1. 1

    Turn the main power OFF.

  2. 2

    If this alarm recurs immediately when power is reapplied, replace the motor (which contains the pulse coder).

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

000Power-Down Required Parameter011Zero Feedrate Specified013Maximum Feedrate Zero
Source: Fanuc Alpha i series AC Servo Motor
Open Manual (Page 224)Search more codes in this manual