FANUC Alarm Codes & SRVO Troubleshooting

Search common FANUC robot alarm codes, SRVO faults, safety issues, mastering problems, and field-proven fixes from real production environments.

Use this first: record the exact alarm code, group, axis, what the robot was doing when it faulted, and what changed recently. Many robot faults are wiring, tooling, safety, or dress-package problems before they are major component failures.

Search FANUC Alarm Codes

Alarm Plain-English Meaning Common Checks Page
SRVO-018 Brake Abnormal Brake wiring, axis brake circuit, robot harness, servo amp, robot arm cable, external tooling, weld gun power cable connections. Open SRVO-018
SRVO-037 IMSTP Input External stop input, UOP signals, PLC safety logic, E-stop chain, safety relay, Ethernet/IP mapping. Coming Soon
SRVO-038 Pulse Mismatch Pulse coder, mastering data, axis position mismatch, battery loss, improper mastering. Coming Soon
SRVO-062 BZAL / Battery Alarm Robot batteries, pulse coder battery circuit, mastering data, battery replacement procedure. Coming Soon
SRVO-075 Pulse Not Established Pulse coder reset, mastering, battery loss, encoder position not established. Coming Soon
SRVO-105 Door Open / E-Stop Related Fault Door circuit, external E-stop, safety chain, IMSTP, fence circuit, safety inputs. Coming Soon
SRVO-230 Chain Abnormal / Safety Chain Issue Dual-channel safety circuit, E-stop chain, safety board, fence/door inputs, external safety devices. Coming Soon

Start With the Exact Alarm

Write down the code, group, axis, and full alarm text. For example, SRVO-018 on Group 1 Axis 2 points you toward a specific axis-related brake abnormal fault.

Do Not Replace Parts Too Fast

Many robot faults are caused by wiring, external devices, safety inputs, cables, connectors, water intrusion, dress package damage, or tooling issues.

Field Verified Fixes

This database includes real production-floor fixes that may not be obvious from the alarm text alone.

Featured Field Fix: SRVO-018 Brake Abnormal

Colotti Automation Field Verified: A FANUC robot showed SRVO-018 Brake Abnormal on Group 1 Axis 2. The fault occurred while trying to move the robot, even when it was not welding. The root cause was tied to a broken, wet, dirty, or contaminated weld gun power cable connection.

This is the kind of fault that can send a team down the wrong path replacing brake hardware, servo amplifiers, or robot harnesses. On welding robots, inspect the weld gun power cable connections and dress package before assuming the brake circuit is the only possible cause.

Read Full SRVO-018 Troubleshooting Page

Basic FANUC Robot Fault Troubleshooting Flow

  1. Record the exact alarm code, group, axis, and full pendant message.
  2. Identify whether the fault happens while jogging, during automatic motion, during welding, during homing, or at power-up.
  3. Check what changed recently: cables, tooling, servo amp, batteries, weld gun, dress package, safety device, or program change.
  4. Inspect connectors, cables, moisture, contamination, loose terminals, and grounding before replacing major components.
  5. Use OEM procedures for electrical checks, mastering, battery replacement, and servo troubleshooting.
  6. Document the final root cause so the same downtime does not happen again.
Safety reminder: Robot troubleshooting can involve stored energy, servo power, brake circuits, weld power, pinch points, and hazardous motion. Follow lockout, safety, and OEM procedures.

Need help with a FANUC robot fault?

Colotti Automation can help with robot faults, production downtime, PLC issues, vision systems, and real-world troubleshooting.

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