Hi there, the scion T1819 head unit fr scion '12 is not a plug and play. You need three conversion cables that you can get from trdsparks.com
Here's the list
Conversion Cable antenna PT546-00120-AD $23.50
Conversion Cable : 20pin + 8pin to 28pin PT546-00120-CH $31.50
Conversion Cable : USB PT546-00120-US $59.50
I'm still in the dark on how to make the Blutooth works. Pls post when you find solution for it, thanks