2003 Suburban Bose System

I am wanting to add a LOC to this system, BOSE in a 2003 Suburban, so that I can add an amp and subs.

I hooked it to the rear pillar speak just inside the rear hatch on the left side. It has a brown wire / YELLOW wire at the plug. I am assuming that the brown is + and the yellow -. I hooked the RCA's to the LOC, the ran the up to the amp. With the stereo on, I plug the RCA's into the Rockford 500.2 amplifier and the speakers on the left rear side (left rear passenger door, rear pillar) both quit working. What gives and should I be hooking this up elsewhere. It is just a basic non-adjustable LOC, nothing fancy. I would hook this to the back of the factory 6 disc deck, but was told by someone that I should not mess with the factory head unit as it is hooked to OnStar and could really foul things up. Thanks for any help as I am stumped!

If it's a bose system, there is not low frequ. going to the regular speakers.  Those signals have already been crossed over at the factory amp.  You must find the factory sub and tap in there.  Should be under the console or in the side of the back cargo space.

Billly

I have looked in the rear side side panel behind what would appear to be where a factory sub would be, but there is nothing there. I would assume that it would have to be under the console, yet I pulled the drink holder out and dont really see anything other than one big bunch of wires and a black plastic square enclosure that I suppose could be a small sub enclosure.

Could it be possible to pick up the signal from behind the deck instead? Thanks again for the post!