Feedback through speakers

[andrewnriley]

Feedback through REAR speakers

Hey I know there are similar posts on this, basically I am adding an aftermarket amp and sub to my 2010 tahoe w/bose premium sound. I bought the PAC GM1416 adpater that allows you to add RCA out from your stock head unit.
I ran power, rca, and remote wire and before i put the stereo back in, i wanted to make sure it still was working! It worked fine but there was feedback, which i figured was coming from the PAC adapter. I bought a ground loop isolator, which has rca in and out and two extra wires?? (for remote? ground?) Anyways, I didn't have time for now to pull apart and put the adapter in, so I plugged in the stock connections to the head unit so everything is back to stock, except that I have power (not hooked up), rca, and remote all running to the rear of the car. No extra wires are hooked up at all, and yet I sitll have this damn feedback coming from my speakers!! It makes no sense, unless there is an extra wire that goes to ground that i missed behind the head unit that somehow came unplugged???
The whole stereo is back to its stock condition right now, but i'm getting a whine (based on rpm). Obviously ground issue, but why, when i have nothing extra installed.
Thanks,
Andrew

 

[andrewnriley]

pics/ schematic

 

[carlosg773]

I always use a separate isolated ground point for my head units. Try tapping in to existing ground and using an auxiliary ground to a closer unpainted surface to the head unit if you don't want to change the stock condition. You may have inadvertently pulled the ground and loosened it from its terminal. It's hard to tell because the ground terminals are not visible which is bad to begin with (l

 

[andrewnriley]

Hey Carlos, thanks for the reply. I forgot to mention, that the whine in the speakers is ONLY in the rear speakers.... If I just turn on the rear passenger listening mode, it cuts them out and the whine goes away, but its not the solution to the problem at hand. So I took out the center console to run a good ground from the head unit to chassis. There were plenty of good spots to run to the chassis by the stock amp/sub, and even up under the dash on the framing. I even did a continuity test from a bolt i picked to chassis and it was good. So in the process of removing the center console, i got to the rear passenger stereo unit, and come to find out, one of the pins got bent when i connected it up last time! Ffffuuuuuuuuuuun. So that was causing the ground issue, because there was no pin connected! So I have a whole arsenal of micro tools to hopefully straighten it up without really weaking it any more.... more than likely though, that pin is gonna be very malleable now, which sucks... So I might have to buy a new rear stereo unit, OR, i bust into my EE scrap and pull out some new header pins, rip apart the head unit and solder a new pin on there...hmmmmmm.

 

[andrewnriley]

Just a follow up, I straightened the pin out very very carefully, definitely able to tell the pin is much weaker, but connected the rear head unit back up very gently and got a good connection....So hopefully there's no need to disconnect again in the future, dont want to deal with that **** again.
Thanks,
Andrew