I am replacing the radio.

Stereo Wiring
Constant 12V ..................................................Orange Switched 12V ................................................. Yellow Ground Black Illumination.....................................................Gray Dimmer............................................................Brown Front Speakers 6 1/2" Doors Left Front ( ).......................................................Tan Left Front (-)........................................................Gray Right Front ( )......................................................Light Green Right Front (-).......................................................Dark Green Rear Speakers 6 1/2" Rear Doors Left Rear ( )...........................................................Brown Left Rear (-)............................................................Yellow Right Rear ( )..........................................................Dark Blue Right Rear (-)...........................................................Light Blue
First of all, the Bose amplifier needs to be activated when the after-market head unit is turned on. This is done by connecting a activation wire (often called a "remote" wire) in the factory radio plug. Usually this is a dark green or orange wire in the main radio plug, but in Onstar-equipped vehicles, the remote wire may be pink or orange in the smaller, secondary plug. In either case, the wire must be connected to the blue/white remote output from your new head unit, in order for the Bose amplifier to turn on.

If all you're doing is replacing the radio, I would recomend going to some place like Best Buy and purchasing the harness they sell. It splices into the radio harness and then simply plugs into the existing harness of the vehicle so you don't destroy the integrity of the vehicles harness. Runs about $20. If you still need a wiring diagram. let me know and I will see what I can find.

Its quite easy actually you dont need a diagram all you require is a multi meter.

To find main power wire.
1.) connect the negative lead of your tester to the ground (grounding point) any metal part attached to the car body will do.
2.) with the keys out the ignition, touch the positive lead to every wire until you find the one with 12volts.
this is the main power wire.

To Find Ignition Wire.
1.) connect the negative of the multimeter to the car ground or grounding point.
2.) turn on ignition.
3.) touch every wire (except the main power wire) until u find one with 12 volts. Turn the ignition off and this wire will now read 0 volts. turn the ignition back on and it will now read 12 volts.

Thats the ignition (axcessory wire)

ground!'
any metal part of the car body. attach it to a bolt or screw.

Speaker wires!

Easy
unbolt every speaker and see which wires are connected to it. or you can use trial and error connecting 1 speaker at a time.

e.g pruple, purple stripe.

These wires are attached to the jack that connects to the original car radio.

On your new radio there are wires that have marks, just use one pair to connect to each set of wire on your vehicle. for eaxmple: lets use the blue and blue with black stripe on the radio. chose a pair on the car that lets say brown and brown with white, connect brown to blue brown/white to blue/black. now listen to which speaker on the car has sound then connect the brown and brown /white respectively to the pair on the radio that has the mark.
do it for the rest of the wires

Check old radio sometimes they have schematic sheet on outer casing