2009 CTS ignition on switched wire in dash
 

I am using the always on dash cigarette lighter for an accessory for my stereo and I would like it to be off when the key is out. I am going to wire in a 20 amp 12vdc relay under dash but I need a ignition on hot wire. The contacts of the relay will just be in series with the already 20 amp lighter wire. Just need an on wire.