Flashing LED alarm light

I have a flashing LED in the dash which was attached to my alarm which I have removed (I still have an immobilizer fitted) I want to leave the LED where it is (or I will have a hole to fill) and get it to flash when I stop the car, I can get it to flash by wiring up the 2 wires but it flashes all the time even when driving.
Is there somewhere I can get power which is only on when the car is switched off?
Thanks.
 

I think you need to put the live wire on the led to an ignition live which then becomes an earth when the ignition is switched off.

poke around with the wires in the hazard switch, there is a one that is live when ign off, find that and a common earth and you have a cheap alarm that won't go off by mistake when its windy or another car drives past.

grey wire on ignition switch is only live ignition off, or if not there its pin P on ignition switch