How long does this procedure take?

Diagnosing a FANUC Brake Slip Fault (SRVO-018) on R-30iB is rated Advanced and takes about 50 minutes across 6 steps.

What tools do I need?

You will need Teach pendant, AC servo motor manual with brake specifications.

What should I do before starting?

A SRVO-018 Brake abnormal alarm, a BRCH-001 through BRCH-010 result, or another symptom pointing at brake holding capability.

Troubleshooting workflows

Diagnosing a FANUC Brake Slip Fault (SRVO-018) on R-30iB

For maintenance technicians investigating a FANUC SRVO-018 Brake abnormal alarm or a BRCH brake check failure that indicates an axis brake is not holding to spec.

Advanced~50 min6 steps

Capture the alarm and symptom

Record the exact alarm (for example SRVO-018 Brake abnormal) or the BRCH result code, which axis and group it applies to, and what the robot was doing at the time.

Run the BRCH brake check function

Use the documented software brake check (BRCH) function to validate brake holding. The check compares measured holding torque against $BCK_GRP[group].$BRK_TORQUE[axis] for the affected axis and group.

Confirm the torque threshold against motor specs

Verify $BCK_GRP[group].$BRK_TORQUE[axis] matches the BRAKE SPECIFICATIONS value from the AC SERVO MOTOR manual for the motor installed on that axis. A wrong threshold can cause false pass or false fail results.

Review BRCH result codes

Interpret BRCH-001 through BRCH-010 results per the documented meanings to narrow the fault to a specific axis and condition before escalating.

Escalate a confirmed BRCH failure

If BRCH fails or SRVO-018 keeps returning, treat the robot as stop-use and hand the axis off to a qualified technician for inspection and repair per the FANUC service documentation. Don't attempt field-level brake disassembly from this guide.

Retest after service

After qualified repair, rerun BRCH and clear SRVO-018. Confirm a clean pass on the affected axis before returning the robot to production.

Common questions

How long does this procedure take?: Diagnosing a FANUC Brake Slip Fault (SRVO-018) on R-30iB is rated Advanced and takes about 50 minutes across 6 steps.
What tools do I need?: You will need Teach pendant, AC servo motor manual with brake specifications.
What should I do before starting?: A SRVO-018 Brake abnormal alarm, a BRCH-001 through BRCH-010 result, or another symptom pointing at brake holding capability.
What is the first step?: Capture the alarm and symptom. Record the exact alarm (for example SRVO-018 Brake abnormal) or the BRCH result code, which axis and group it applies to, and what the robot was doing at the time.