New to the Forum...
 

Hello everyone. New to the Forum. I have 2003 H2 Hummer and I'm beginning to tear-out all the old and put in new. I'm at the sound/stereo stage and am installing an Alpine stereo that has a Sirius XM kit that plugs directly into it. I'm familiar with the radio antenna on the right, but I'm curious if I can wire the existing GPS antenna (same as an XM antenna) into the XM kit antenna, instead of putting their square puck on the roof. I also have a third antenna, attached under my review mirror, but I think hat may be part of the old alarm system, which had a remote kill switch in it. Any insight is appreciated. Thanks.

Hi Jake and welcome to the forum...
To your questions, start with contacting Alpine.
Crurchfield ( a seller of Alpine) has great customer tech support. For helps.

Sure can. Do a search on the net, YouTube. I installed a Pioneer and SiriusXM. Don’t remember all the details but basically take the pink I believe outside shell off plug and plug it in.

One of my old posts details doing that. Will have to search to find it (I would have to as well). But yes - you can repurpose the factory Onstar GPS antenna AND you can also repurpose the factory Onstar microphone too. You will have to reroute the cables from the Onstar module to the stereo area and splice on the correct type connectors is all. I know different brand car stereos use different GPS and mic connectors. Mine is a Kenwood. You might also be able to find a GPS connector adapter cable like on eBay to go from the stock connector to whatever connector the Alpine needs.