This article from the Apple Knowledge Base:
Reset the System Management Controller (SMC) on your Mac
describes very well which kinds of events are symptoms which might
be related to an SMC in need of a reset. But the relationship isn't
clearly established.
Is there any simple method to diagnose clearly the SMC state:
- is it OK?
- does it need a reset?
Something like (for NVRAM):
nvram -p
or
nvram -p | diff /etc/nvram.backup -
Best Answer
Your best bet is to go through Apple's diagnotic utilities, but be prepared for it to tell you everything is fine.
Put you machine on a flat stable surface and plug it in. Perform a restart or a power on and immediately hold down the 'd' key (d for diagnostics). It should at least test your power adapter which is goverened by the SMC chip.