Fire Alarms "Click"

So I noticed on the Integrity and Genesis series they do a short click before doing Code-3. Why is this?

It has to do with synchronization. Some Wheelock horn/strobes do this as well.

I have also noticed this with the SpectrAlert Advanced (the 2 wire horn/strobe version).

Could the click be the strobe getting ready to flash?

Not likely; at the very least the horn-only Genesis units do the same thing.

With the SpectrAlerts, it is the horn getting ready to sound.