Try one of these two options...
Pull the RFA MOD fuse from the passenger fuse panel start car cycle through the bands then shut car off and put the fuse back in, repeat the process and see if xm returns.
If this does not so the trick pull back the carpet on the left side of the trunk, and unplug the xm module and re plug it back in.
If all these fail unhook the battery for ten minutes and rehook up.
Sometimes the xm modules goes unresponsive and goes missing from the band button. Disconnecting power has solved it in any case ive seen.
The six disc is well capable of XM, as well as the single disc and nav.
Ive added XM on my 04 with single disc, and on my06 with 6 disc and when I upgraded to nav the xm stayed as well.
As long as the radio has a "band" button it is factory xm capable,If it has only an am/fm button it is not capable.
Typically model year 03 and up radios are xm capable.
