Fanuc Spindle Alarm 89 (Submodule SM Abnormal — BiS Synchronous Motors) — Causes & Fixes

Fanuc spindle alarm 89 means the submodule SM (SSM) is abnormal — issued on BiS-series synchronous spindle motor systems. The SSM is the add-on module these permanent-magnet spindle configurations use alongside the amplifier; the alarm means the amplifier cannot work with it. Fanuc's triage rule mirrors AL-65: at first start, all causes (a)–(d) apply; on a machine that has been operating normally, only (c) and (d) — configuration cannot have changed by itself.

Commissioning / first-start causes

1. (a) The amplifier does not support the SSM: the amplifier model/version fitted is not SSM-capable — a specification mismatch from a swap or an incorrectly chosen replacement. Verify the amplifier specification against the BiS system's requirements; the fix is the correct amplifier, not persistence.
2. (b) The SSM is not mounted or connected: check the interface cable between JYA4 on the Spindle Amplifier and CX31 on the SSM — present, seated, latched at both ends.

Any-time causes

1. (c) The JYA4–CX31 interface signal is disconnected: the same cable, failed in service — reseat both ends, inspect pins for damage and coolant, walk the run for crush/oil damage, wiggle-test. Replace with the correct spec cable if in any doubt — the standing rule for signal cables.
2. (d) The SSM itself is faulty: with the cable verified, replace (or bench-repair) the SSM.

Related guides

• Fanuc spindle alarm 65 (magnetic pole detection — BiS)
• Fanuc spindle alarm 90 (unexpected rotation state — BiS)
• Fanuc αi drive alarms — PSM, SVM & SPM codes