Onstar Adaptor Removal Issue, 2005 Chevy 2500HD

Hey all,

Sort of a newbie to this site, been here before under my friends name, anyhow looking for ideas for an issue I have, I have a 2005 Chevy 2500HD w bose and onstar, back when I got the truck i swapped in an Eclipse AVN-5495 nav DVD unit, I had this unit installed at shop I was not familiar with in Vegas when I was out there for a few months, I then returned back east and installed a ton of stuff, head rest monitors, alarm w remote start, all new door speakers with 4 channel alpine amp and subs on a mono amp, ths was all done at the shop I usually go to before getting my shop built then I have done my own, I write all this so you understand there have been a few hands in this cookie jar.....I have to trade the truck in a week from today and so far I removed everything and replaced all stock, problem is the front speakers are not working, however I do get door chimes, and sound from the rear even when the radio is faded all the way to the front??????

When I had the shop add the door speakers and amps they installed a PAC-OS-2 onstar adaptor which worked for awhile then got garbley one day and i honesty never used the onstar so never really cared much and just left it be but when you do hit the button it sounded like the voice was coming out of the factory sub woofer only (there are no external speakers under the dash) turns out it was hooked to fact tweeters and sub and for some reason the tweets quit and that is why I could no longer hear it 2-3 years back when it started acting up??? When i first installed the fact head unit and turned it on all i had was the rears playing, and only about half volume, then I noticed that when i faded to the rear they quit and when i faded to the front it was playing out the back at the half volume.... I then rememebred to plug the rear radio controller back in and boom the rears were alive full volume, but still no fronts and still the chime was out the drivers rear door and if i faded front the rears were still playing at the same half volume? i traced everything back, I even ran new wires from the fronts to the factory bose amp, but this did not help, they will work if i hook them to the rear so the wires are not the issue.

I went back over to the original shop but my friend the owner is super busy with christmas coming and in the 20 min he looked we could not figure it out, he gave me a few ideas to try but to no avail, he then said that the installer that did my work back in 05 has been gone awhile....but ironically enough I ran into him at a gas station 3 days later, turns out he moved with in 10 minutes of me and this morning came up to have a look and try a few things, and again to no avail, we have come to a point where I believe one of 2 things is happening unless someone here has a better thought??? Keep in mind back in 05 I was one of the first here to do a swap with onstar and bose to a nav DVD unit so I was a test truck so to speak.

What I believe is that some how the front channels on the fact Bose amp are toasted, perhaps a mis wire of this onstar adaptor burned out the channels or something on the board in the amp that is allowing some sound from the front to bleed into the back, perhaps when i scrapped the fact amp and speaker for the alpine 4 channel some thing should have been changed, the PAC install guide has options for both, and some of the wires on the PAc OS-2 have been cut then nutted back together, so they were either cut by mistake or cut then later re attached when we added the amp??? (they are connected color for color no swaps, at least not now)

OR.... A friend came up this past weekend to wire up a head unit and install that and a remote start in my garage since his lifted truck fits in my garage and when he plugged in the new head unit it had power to the LED light but would not turn on, i jumped in and looked and there was no IGN power lead on the factory harness side, I told him it was probably pulse activated, and I just grabbed an IGN hot off his power port, everything was fine, then on the way home he got a code that was "lost comm w radio" we cleared this and all is good, while talking to another friend he said in his truck he had to swap pin location on the factory harness to make his after market stereo work with the key, this got me thinking perhaps the vegas guy swapped out a pin or two back when he installed the head unit???  I can not seem to find a wiring diagram from the actual factory harness plug to verify all pins are in the plug that goes into the back of the radio correctly.

Right now as I said the rears are loud and clear, if I fade to the front the rears still play at half volume and not quite as clear, and all chimes and onstar will play out of the rears, but zero to the front, I have removed the entire console and verified that nothing from the radio to the amp has been spliced into, we removed the after market wires from the amp to the tweeters that was being used by the OS-2 for on star w after market head unit, we even un plugged the tweeters from the factory plugs incase one of them was blown and grounding out the front channels. What I am looking for is a wiring diagram for the factory harness and pin locations on the radio plug or suggestions, I did find a used bose amp, but really do not want to spend 75 bucks and a 4 hour round trip drive and risk that not being the problem any help would be greatly appreciated on where to find a diagram free or even not, or any other ideas??? I just find it hard to believe I have this issue, and I could rig all 4 speakers to play enough for the trade in, but it bothers me to just pass this issue to the next guy, plus it bothers me to not be able to fix it period. Thanks all, sorry it got so long, figured it would save some questions though.