Finding Power in 02 Tahoe for XM

I hope someone out here can give me some help.  Electronic aren't my strong suit so as I read through some of these postings I think I've found info that will help me but I just can't be sure.

I own an 2002 Tahoe Z71 with a single CD and cassette and I'm getting ready to install an XM SkyFi2 unit that I got for the holidays.  I think I'm fine with everything I need to do to connect the receiver to the radio and install the antenna but I'm confused as to what I need to do to hardwire the power.

I was thinking that I could either tap into the power and ground from the radio or or from the cig. lighter.  If I use the radio what wire do I need to tap into for power?  Will this allow me to use the RAP feature that turns the radio off when the doors open?  I've read some stuff about the radio ignition wire being dark green and the 12v wire being orange.  Which one of those do I want to use?

If I tap into the cig lighter will this drain the battery since it's a constant source of power?

Any help would be really appreciated.

First off, you should get a multimeter to allow you to verify all of your wires before you make the connections to them (for safety reasons).  Just a note, the skyfi2 only needs a switched power connection (as well as a ground, of course) in order to work.  In fact, this is the preferred method of hookup as it will make it turn on and off automatically whenever the car is on or off.

What does the wiring harness plug for your factory radio look like?  Is it one like this?  or does it look more like this?  If it's the first one, then your radio harness probably does not have a switched power wire in it and you'll have to search for one in the ignition harness.  I believe it'd be an orange wire in the ignition harness but I'm not 100% sure for your particular vehicle.  Verify with a multimeter.

If your plug looks like the 2nd one, then you should be able to get the switched power wire by tapping in to the yellow wire.  Again, make sure this is correct by testing it with a multimeter first. 

All of the factory plugs will have a constant power wire that you could use as a last resort (usually orange in the radio harness), and then you'd just use the auto-off feature of the skyfi2 as described at  Crutchfield's SkyFi2 page: 

Auto On: Normally the receiver turns on whenever it receives power. If it is wired to a power source that is constantly on, you can disable the Auto On function.

Auto Off: You can set the SKYFi2 to automatically turn off 15 minutes to 3 hours after your last input or action. This feature is helpful if the unit is connected to a constant power source. The Auto Off feature can also be used as a Sleep timer to shut off automatically after a period of time.

 pink, eh?  well I guess I could very well be wrong.  But like I said, verify the wires first with a multimeter

Figured I'd post this so folks in my same situation know how to find RAP power in a  2002 Tahoe.

The dark green wire coming off of the main radio power harness is a 12v RAP wire.  I don't know where to find a diagram of the plug but it was the second wire over, right beside the orange wire.  Now when I turn the car on my XM receiver powers on and will stay on until I open the door, just like the factory radio.