FANUC Alarm SRVO-018 — SERVO Brake abnormal
Error- Hardware
- motor brakes
- Controllers
- R-J3iB / R-30iA / R-30iB
- FANUC class
- SERVO
- Hardware family
- FANUC brake, fuse, robot signal and position error alarms
FANUC SRVO-018 (“SERVO Brake abnormal”): The brake current has exceeded the specification. First check: 1. Verify that the RM1 cable that carries the signal wires from the controller to the robot is securely connected and that the pins and cable are not damaged. Likely part: Servo amplifier (Servo amplifier).
Updated 2026-10-22 · LogrobotLM reference
Description
The brake current has exceeded the specification.
Remedy
1. Verify that the RM1 cable that carries the signal wires from the controller to the robot is securely connected and that the pins and cable are not damaged. 2. Check the brake cable 3. Replace the servo amplifier if it is not working.
Field diagnosis
The brake current exceeds the specification: short circuit or ground fault in the robot connection cable, the internal cable or a brake coil.
What to check
- On R-30iB the amplifier alarm LED lights up.
- Measure the insulation of the robot connection cable, the internal cable and the brakes connected to the amplifier (connector CRR88); replace the faulty item, then the amplifier.
- Note: An auxiliary axis brake wired to the wrong output trips this code at the first motion command.
Part to check / replace
FANUC SRVO-018 points to the hardware below — start here before ordering.
Tap a part for every code that points to it — and verify the exact variant for your controller before ordering.
Related codes
Same hardware involved
Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. How this reference is built →