Its not what you think. I have installed stereos before in my cars and I know the red and yellow wires but this car has done this with more than one stereo. In fact all three stereos have refused to hold presets and I am inclined to blame the wire but I don't know where the other end ...well ends. What I am actually asking is how do I fix the constant voltage wire the stereo is attached to? Is it something I fix without having to tear out my dash?