Today I witnessed the beginning of my 2001 IS300 start flashing it's blinker lights after I shut off the car. At first it was just hesitating and a slight flash, but now a short time later it's full blown flashing as if I have the hazard lights on. The only thing that makes it stop flashing is to start the car, otherwise it would just sit there and flash until the battery dies. I pulled my negative battery terminal for the time being while I came in to research this issue online, but it appears to be a failed turn signal relay. I'll update this thread if that fixes the problem so that others can search for this in the future.