Stereo install

the orange w/white stripe is usually a trigger wire for an amp, power antenae(?), or a cd changer. you need to check the manual that came with the head unit to be sure. also usually the wires are marked as to where they go. if you dont have the manual, you can write the manufacturer and tell them the model number of your unit and they can send you a manual.

The Ill is the illumination wire. When you turn your lights on, the face lighting adjusts so you can see it better. It really doesn't do all that much. I thought the blue wire was the antenna lead, but I could be wrong. You can go to the Pioneer website and see if they have a manual you can download. http://www.pioneerelectronics.com/pna/product/manual/0,,2076_4277,00.htm

I know what you are asking.
But Im not sure of the exact answer but with a VOM (Volt/ohm meter) you can easily determine which factory wires are what. You can buy these meters anywhere for as little as 5.00. The local auto parts store stocks them too..

To find the Ground (black) just do an ohm measurement..Touch 1 lead to the chassis and the other to each of the factory stereo wiring until you find one that reads "O".
Then to find the continuous power wire..Turn the meter to DC voltage. Touch the black lead to the ground wire that you found...then touch the remaining connections until you find one that has about 12 volts all of the time.
For the switched wire just leave the black lead touching the ground wire and then touch a remaining wire-then turn on the key...When you find one that goes to 12volts when the key is switched on then you have the switched wire!

Speaker wires should be easy to find..However, you probably need to run new wires since you are using a much higher powered receiver.

red = switched ignition
yellow = constant +12v
black = ground
orange w/white = dimmer
blue = amp or antenna trigger (or both! use diods to separate)

speakers:
*all black stripes are negatives*
greys = front right
whites = front left
greens = rear left
purple = rear right

if the head unit has RCA pre outs for an amplifier the red is ALWAYS right and white is ALWAYS left. but then again i guess you could reverse them and be wierd like that

to find a good ground find a spont on our all metal dashes, as they are grounded, and attach the ground to it in a non-descript way. the best way to find a good constant for a high power unit is to run a fused line directly from the battery, the stock wiring just cant handle the extra pull. as for the switched you have two options: run all the time ie. connect the red to yellow on the same line, or get a test light and find the true iginition from the back of the ignition module. its not that hard to find it just ground the test light and find the wire that lights the light when the ign is turned on

hope this helps