A red light is lighting briefly on my dashboard in the RPM indicator area, in my honda accord 2000. The red light appears for a fraction of a second, so I can't tell what it is. Anyone has an answer on why this is happening, and what is that indicator for? Thanks.

It's likely the battery light coming on when the rpm is low, indicating that the battery's drain is greater than the voltage being generated by the alternator.

Have your idle rpm increased.