XM Radio PLEASE HELP!

[kdavis61]

Hey Guys,
So I have a Tahoe z71. The XM antenna is on the top of the car but, when i push band it goes through the am and the fm functions not Xm1 and Xm2. I know my car has this because i looked through the manuel and it clearly states that it has this function.
PLEASE HELP

 

[SunlitComet]

perhaps the tuner was removed. it should be be located behind the glove box behind the junction block. or it could jut be broke.