So I just recently brought this 04 Audi noticed there was a issue with the radio been doing about it reading and seen some people have put a Ignition switch feed to turn them off my question is the only way the radio will work is if red and yellow are together  the stations don’t save and noticed this green and black cable at the back any one shed some light thanks 

Hi i am in the process of fitting a after market HU and i can tell you the Green is for the left rear speaker, I also know that normally the yellow is 12v supply and the red is ignition..

I have it working just not saveing the stations kept red two red then split the yellow and toke a feed from a fuse that goes love with ignition on now radio turns on and off with key like I say only problem don’t save radio stations 

the yellow is the constant live and red is switched. swap them over the red to a live with ignition.