Immobilizer System Indicator

sounds right.

 

Does this stop flashing when car is turned off or continue flashing?
2015 Prius V

 

it keeps blinking to show potential car thieves that there is an alarm/security/immobilizer /

 

It's been a feature since the very earliest car alarms and immobilizers, where the blinking light is supposed to say to a would-be thief "hey, this car has an alarm or immobilizer, go steal that one instead."

Of course these days the thief is choosing between cars that probably all have their little red lights blinking, so probably is going to choose based on something else.