Adding Sirius to 05

I have an 05 with the 6 disk Bose radio.  It did not come with the integrated XM unit but I plan to add the SIRGM1 unit that replaces the factory XM module.  Will my radio automatically recognize this unit or will I have to have the XM function "turned on" somehow?

there are only a few GM models out there that req Sat radio to be turned on within the BCM, fortunately, the avalanches arent one of them. As long as you buy the proper XM or Sirius kit that is designed to plug-n-play with an OEM radio and your radio is sat ready (which it should be), you'll be fine. I dont know if you know this, but XM and Sirius are one and the same now. Doesnt really matter if you get either or. The difference is only between a hand full of specialty channels.

Thanks for the help.  Yeah I know they're the same now.  I found a deal on the Sirius unit for $20 and alread have a Sirius antenna installed from a previous Kenwood unit.  I could not find any deals for the factory XM unit anywhere close to that price not to mention I do not have the factory or any XM antenna on it.

Just so I know what to wire this to I have a small question.  According to the instructions I am supposed to use the T harness since my truck did not come with the factory XM.  On the T harness there is a yellow power wire with a fuse.  Is this yellow wire to be wired to a constantly hot wire?  It said to wire to a cigarette lighter but they stay on all the time in the Avalanche.  Is this supposed to get power all the time?