Audio Systems: question about aftermarket cd player, fuse boxes, blown fuse

Question
Dear Kelly,

    I have a Pioneer DEH-P25 CD player that I am trying to install in place of my factory unit.  My problem is that the deck will not hold my presets in memory or the clock after I turn off the car.  Since I do not have a wiring diagram, I tried to adapt the current wiring to the Pioneer deck.  I have the red power wire from the car connected to the red power wire as well as a yellow wire labeled "battery constant" on the cd player.  I'm not even sure that this is correct, but the radio does work.  There are also three other wires on the cd player that were not used: a wire labeled "dimmer", a wire labeled "turn on", and an unlabeled yellow wire with a black stripe.  I tried to connect each of these wires individually to the power as well and the result is the same - the presets and the clock reset.  If you have any ideas, please let me know at your convenience.  Thank you very much for your help.

    Sincerely,
     Chris F.

Answer
You are lucky that your deck still works. So many people burn up equipment doing what you have just described. First, get a test light or multimeter! radio shack has them for $20. Get one. Now, test you wires for one that does not loose power when the key is off. if you can't find one, you most likely have a blown fuse. You didn't say what vehicle this is, but check both fuse boxes, underdash, and underhood. The other three wires won't be needed in your install. Tape them off so they can't touch ground, or each other.