If the alarm has tripped, it will wait until the first time the ignition is turned on no matter how lonmg that is to display the fault/flashes.
You will know if it has been triggered as it will beep(if enabled) and flash THREE times to show it has been triggered, so you are aware to count the flashes.
Most are set up with no beep on arm/disarm, as it is now illegal due to nise pollution, but this can be enabled easy enough, and has 3 sound levels, but even the quiet is bloody loud.
tabetha