Hi, I was hoping that someone could help me with this, as I am at a loss at how to fix it. I drive a 2007 cobalt lt, I installed an mtx amp, its a two channel amp. I put the 6x9 speaker inputs into the high level inputs, then ran the amp to the two 6x9s. I grounded the amp onto the bolts for the rear seats ( underneath the carpet in the trunk) When I turn the car on, I get a high noise over the speakers( this only happens when the engine is on, when on accessory I get nothing. The amp has a swtich(cross over I think?), for all bass, bass and highs, or just highs. when its on all bass I get no interferance. but as soon as i put it on the combined or highs, it gets that damn noise. I originally had the ground hooked up to the battery, then I read that was a bad spot and believed that was the problem. I then moved it, and still nothing. Any help would be great!

 

What type of head unit do you have?
If it is a Pioneer, that could be causing it. My Pioneer caused a pretty obnoxious sound before I grounded the leads.

Is it a really really really loud sound? If so, I had the same thing happen to me when I installed my amp. I believe I fixed it by adjusting my level (knob on the amp) but I can't recall very well.

Where's EmporerJJ1 when you need him? haha

 

the bolts on the seats is a shitty ass ground. did it make the alt whine when it was direct to the battery?

 

I have it hooked up tot the stock hu. yeah it did, the sound wasnt to loud, the music could drown it out, but was kinda loud if you are trying to have a conversation with someone...

I had it grounded to the same place the battery was grounded. that little post beside the battery that has the large black cable running from the battery. Then the noise came, and I thought it was the grounding issue. Then I moved it, and the noise stuck around.

 

if it wasnt there but all of a sudden "happened" then something changed. bolt might a been loose causing bad ground, rcas broke, amp broke, LOC broke

ect

 

emp where did you ground yours at? j/w....i have mine grounded at the seat bolts and even with the paint sanded down the ground is still **** (ground loop issue)..thinking about extending it to the battery post unless you have a better suggestion.

 

well i have 2 grounds to the frame in the back and 2 going to the alternator in the front

 

i see, so thats where your spare tire is sitting....nice setup. I'm thinking about doing the same but would it just be more practical to ground it to the battery lead if I'm relocating the battery anyways? my optima is just chillin near the spare tire on its side LOL

 

well i dont have a spare tire anymore but ya.... thats for the battery ground. you would want to ground the amp to the battery for sure. sorry i thought u were talking about grounding the actual battery. you always want to ground the amp to the battery when its that close