Sorry, the signal to noise ratio on the forum has been bad lately, so I missed your post.
Unfortunately, you are using the Soundgate adapter. Here is what Soundgate's web site says:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Pioneer to Hummer Part # PIOGM1
The PIOGM1 digital interface allows the connection of an Pioneer CD changer to many 2003 and newer Hummer vehicles when there is no seperate CD changer, XM satellite, or rear seat DVD entertainment present.
https://www.soundgate.com//index.php?request=product.de...tid=88&usereferrer= 1
</div></BLOCKQUOTE>
Any adapter connected to the GM fatory stereo needs to use at least one of the possible factory "setups" (XM, CDX, or RSE) to use as a gateway for the input. The way I read the text from Soundgate, the PIOGM1 uses all of the ports.
Im not a fan of Soundgate products, but they do have a couple of different AUX adapters. One of them might work. I suggest you call them and ask them what will work.
I would suggest you NOT buy an adapter from any other manufacturer as long as you have the Soundgate adapter you now have attached to the system.
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> You may contact SoundGate in a variety of ways. Our corporate headquarters is located in Sheridan, Wyoming and we are -7 hrs. GMT.
Email Addresses
Sales:
sgsales@SoundGate.com
Support:
sgtech@SoundGate.com
Customer Service:
customerservice@SoundGate.com
Product Info:
info@SoundGate.com
Shipping Address
SoundGate
2071 North Main Street
Sheridan, WY 82801
Postal Address
SoundGate
PO Box 6689
Sheridan, WY 82801
Telephone/Fax
307-674-4707
307-674-4819
Office Hours
Monday - Friday 8:00 am to 5:00 pm (MT)
</div></BLOCKQUOTE>
Good luck!