Edit: Ignore what I typed below as I searched for "cb" in my original search query instead of "circuit breaker." The quick start guide does address the "CB light" switch.
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This plane has great documentation overall, though I would like to point out that the question about the CB switch is actually not addressed in either the HotStart Quick Start Guide or the UI Guide. (Nor the official TBM 900 Pilot's Information Manual for that matter.) I had to find the answer here and I originally thought that "CB" stood for "cabin" and not "circuit breaker." So I am very glad that @N265AB asked the question.