Fanuc alarm SV0488: SAFE TEST OVER TIME
safety/dual-check alarm · Fanuc 30i/31i/32i-B
What it means
A scheduled MCC off Test - the mandatory periodic exercise of both MCC shutoff paths in the dual-channel safety system - did not complete within the time set in parameter No.1946. The safety outputs must prove they can kill motor power; a timeout means the shutoff path is compromised. Fanuc directs you to inspect the MCC contactor.
Likely causes
- Welded, worn or slow MCC contactor contacts
- Open circuit between MCF output, contactor coil and *SMC feedback
- Parameter No.1946 window too short for the contactor used
Triage note: Dual Check Safety alarms cannot be cancelled by reset; cycle power after repair.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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Main circuit magnetic contactor (MCC), machine-builder specific
unit · Common cause
Need the part urgently?
Send us alarm SV0488 with your machine details — typical RFQ turnaround is 24–48h.