Audio Systems: help, pioneer unit, home depot

Question
Hello I have a 2002 trailblazer and I recently bought a double din cd nav pioneer   
unit the only problem is /i am having trouble matching wires any idea which are
which

Answer
Easiest way is to purchase a wiring harness adapter kit from bestbuy, crutchfield.com, installer.com or other such sources.  

They are about $10.  Then, of course, you will need the wiring breakout from the manual of the pioneer that you are installing.  

Or, you can trace out the wires with a vom (Home Depot and Walmart have a little vom that is perfect for auto use that is under $10.00).

Also, you can get started using this wiring chart - older than your vehicle, but still useful.

http://www.installdr.com/Harnesses/GM-Wiring.pdf

Best wishes.  Let me know if you need more.

C

PS: If you don't have the installation manual for the Pioneer you can download it the manufacturer's web pages.