Ok I am installing a Sony CDX-F5710. Now I have a Chevelle malibue 71 and I when I purchased the car it did not have the original stero so I am not sure if I am looking at the orgininal wiring or not. So far I have cut the the harness that hooked up the the old stero, now i am left with a black (-), yellow(+) hot when key on engine off/on, grey (+) hot when I turn on the lights on the dash and headlights wich I think are the orginal cable they disapear behind the speedometer. Now for some reason the stero has 3 (+) Red, yellow cables and a orange with white stipe wich is for illumination (not sure what that means) and another one for the ground (-). So in order for it to work I need to hook up the two + cables red and yellow from the stero to the yellow cable of the car and of course the ground, but then both signal lights turn on a very dim light but there on and then if I turn on the signal light the stereo goes off, and if I turn off the signal light the stereo come back on. Why is this is it because of old wiring and the new stero uses up to much energy or is it just a short that I have some where or something? How can I fix thanks

You need to run at least one wire to the fuseblock, why not run two. Your stereo yellow wire doesn't go to the car yellow wire. It's a constant hot lead for the memory and clock.
Run stereo yellow to the fuseblock "BAT" terminal.
Run stereo red to the fusblock "IGN" terminal.
Stereo orange sounds like the stereo lights wire. That goes to car gray or the fuseblock "LMPS" (lamps) terminal.
The stereo also sounds like it's lacking a good ground. Screw the stereo ground wire onto a clean spot on the metal dash frame.
To connect wires to the fuseblock you will needs some 1/4 terminals. Places like Kragen auto parts sell a small box of them for around $3.00.

Hey thanks a lot just in time to work on it again!

Ok it worked but can you tell how come I have to go the fuse box and not use the cables that were going to the other stereo? And also whats the orange and white cable for it says I ilumination but what for if it iluminates with just the other two cables? Or is there something else that it needs to Iluminate or is it if the car has some sort of dim system for the dash?
Let me know thanks a lot

John hit it right on the head.

I suppose you could have used the yellow for your keyed power but I doubt that puny wire would carry the current necessary for a modern system like the one you are installing. As he said, the yellow needed a constant power source for the deck's memory. Your lights acting up sounds like a poor ground (poor grounding sometimes shows itself in wierd ways). The black from the harness should've worked in theory, but these old wires are often questionable. The orange should go to the grey which will connect it to the dash light circuit.

I have a question for you - what type of installation kit did you use to mount it where the old radio was? How big a deal was it to cut the dash? I'm about to do the same for my son's '72.

Well actually I did not do any cutting I liked the original look so I kept the stereo, actually I wanted to go fancy with it like have it hide and pop out under the dash but the dash does not have room to do that and plus to much work. All I am going to do is hang it under the dash right bellow the stereo

Mounted mine in-dash. Came out pretty good. Not that big of a deal. Cutting the dash was a hard decision to make but it is a basic sweep dash so I got over it quick. Actually got the same Sony model as you at a pretty good price.