ok, i'll give the whole rundown, cause if i just ask my question, you'll wonder what the heck for.

I have a 92 Park Avenue. Has the Delco system and is advertised as "Concert Sound II". I have installed my complete system- which the components are listed in my sig. All of the aftermarket stuff is in addition to the factory. I did not remove any factory stuff- built a console that holds the source stuff, kick panels...

My "rear" speakers for my system are the Alpine 6.5'* in small boxes in the trunk for tailgating, etc. They are normally off- only on when the trunk is open. i have wires that go from the amp to a switch box- Here i have split the wires so that i can run only the front stage speakers, or turn them off, and turn on the rears, or turn them all on. Its a small box with a switch in the Positive for each speaker. If you're following me, this means, that when i have one pair on, the amp is at 4ohm, if all four speakers, then 2ohm per channel.

OOOOK. I decided to try to run the rear factory 6x9s with the rear speaker leads from the amp. I figured if the Delco system is off, and i put power to those speakers, they would play with the aftermarket system. They did, but very strangly- apparantly there is a common negative or something- when one was hooked up, the other only needed one wire to work, but it wasn't playing stereo... it was goofy, so i decided to forget about it, and unhooked what i had done- i only T-Tapped into the lines- never cut. I went to turn on the Delco system again and no sound comes out at all- none of the speakers. the radio is on- display says it should be playing, but its not. no fuses blown in the main panel, no fuses at all behind the factory deck...??? What is malfunctioning?? Anybody know what i did to the factory system? did i overload the circuit board inside the deck??

Thanks for any help, sorry for the novel...

Jeff

the concert sound II might have an amp powering the rear speakers

i'm guessing that you fried your factory deck! it was never intended to have anything fed back into it...it'* supposed to do all the feeding what kind of GHETTO system do you have!!! 2 head units? switching back and forth from factory to aftermarket stereo.... wow! if you're going to do crazy crap like that you need to ISOLATE the sources! i'm surprised you didn't hurt your amplifier doing this!

I hate to tell ya, but I'm pretty positive that the internal amplifier is now shot inside of the factory deck. I've seen this happen before personally..