If anyone is interested, I did get this to work on my car with factory keyless entry. I found the wire on the keyless entry receiver that fires the dome light relay and added a second relay (diode wouldn't work) to fire the park light relay. Now when I lock or unlock my doors, the dome lights (map lights in my case) flash AND the park light flash. It would be easy to honk the horn or flash the head lights too, but I chose to flash the park lights, less annoying. All together it cost me about $6 (and a lot of time to find the right wire).