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  1. #1

    Default Another stereo question...

    Ok, I want to say from the beginning, I am REALLY trying to use my current setup if it's possible. I really don't want to run anymore wires through my truck right now. I just got a new puppy and training her while taking care of the 3 kids (one husband, 2 daughters, lol), I just don't have alot of time lately for my stuff :(

    Anyways, I popped back on here after ahile to see how everyone is, and decided I may as well get you guys' input..maybe I'll find a few minutes.

    So, here's the problem:

    I have an aftermarket amp and subs hooked up to my factory in dash changer and stock Bose system (using a Chevy OEM part). I have it grounded to a cargo strap tie down in the back there, and my 12V is running off a junction under the drivers' side backseat.

    After spending awhile trying to figure out why my amp kept cutting out (mounting location of amp directly on speaker enclosure), it worked quite well for a couple weeks. My husband was very jealous ;)

    After a couple of weeks, I was driving through town one night, and I had the stereo down pretty low. I heard an interference sound coming through my subs, that didn't correspond with the music. It was still there when I turn off the radio. The only way to eliminate the sound was turn off the truck completely or pull the fuse and take power from the speakers themselves.

    I checked the connection the next day, nothing weird. Disconnected and reconnected anyways. It didn't help.

    I don't remember anything being different before and after (ie a/c on/off, onstar, etc) My A/C is on and off all day depending what I feel like, so I know it was both on and off before and after the issue. I don't use the OnStar, and I know at the exact time I first heard it I wasn't doing anything different. I had just pulled up to a red light, so it could've been making the noise before that and I just heard it then...

    So since then (it's been a couple months), my speakers have just been a huge paperweight in the cargo area...

    Life got busy, speakers took the backseat (kinda literally) and I just haven't gotten around to it yet.

    Any suggestions are welcome, maybe it'll get me out there fixing it faster if I have a plan ;)

    As always, thanks everybody!!!

    '05 Trailblazer LT

    Heartbeat of America!

  2. #2


    Double check your grounds. Make sure that it is a solid connection and it didn't get knocked loose.


    '94 Chevy Suburban K1500
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  3. #3

    Join Date
    Aug 2008
    East of Branson, Missouri
    Blog Entries


    Rachel, unfortunately it sounds like the problem, if I'm understanding the setup correctly, is the way in which you have your amp set up. Amp power should always come from the battery. Trying to run your amp from the any junction or fuse cluster is pretty much a no-no because if the amount of power it takes. It's pretty much like plugging your electric stove to an extension cord and running it to the surge protector where you have all your computer equipment plugged into in the living room.

    I know it's now what you necessarily wanted to hear but I think that MAY be the issue. Maybe line noise in there somewhere.

    I totally understand not having time to mess around with anything like that due to a busy time, but I would really suggest you bite the bullet on this one and take it in to a local car audio place and letting them tell diagnose what the issue is and letting them fix it. At the very least they should be able to run a suitably-gauged wire to the amp for you from the battery.

    I will honestly tell you I'm not a professional installer of car audio equipment, but on two separate occasions I've gotten to personally see bad wiring take it's toll on vehicles. One just made for bad audio from the speakers... the other was a 'bad amp' that kept going faulty. The owner (I was lending a hand at a body shop during that time) lamented that the amp was total crap and he needed to get a new one.. blah blah blah. It was a Blaupunkt... So while I milled around I had a look and he had it wired to the trunk light's 12V power - I kid you not!

    "12v is 12v... shouldn't matter where I jump it to."

    I didn't even bother trying to explain it. pfffffffft!!

    Anyway.... good luck with your issue, I hope it gets resolved. Nothing better than good sound in your vehicle while you're zooming down the road - nothing worse than bad sound no matter what!

    "The Sarge"
    1999 Chevy Suburban LT- K2500
    7.4 454 Vortec, 4WD
    305/70/16 on Eagle Alloy

  4. #4


    Thanks Spring. May not be what I wanted to hear, but I'd always rather have the truth. I was pretty much sure that's it to. My hope held out that for a while there wasn't a problem with the setup, and that there was something I wasn't seeing.

    I guess for the moment I'll double check my ground. I had to scrape paint for it, so maybe an extra scrape or two will help.

    Unfortuneately after that, I'llprobably just run without the subs, I just don't see the time, and I do not have ANY reliable stereo places in town, so odds are I won't be doing that.

    Appreciate the help, guys.

  5. #5
    Sr. Apprentice goodie's Avatar
    Join Date
    Jan 2009
    Midland, Tx


    Ya, you need to run a fused power wire from your battery to the amp...your remote wire can be any 12v source but the power input needs to be a hefty wire from the battery. How much power is your amp? If its under 1000 watts I'm sure you could do with 4ga wire

    And definatly make sure your ground is a solid source...grounding to the frame is the best. Or you can even run a ground from your battery if you feel like it.
    2006 GMC Sierra 1500 4.8L V8
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    2004 Mustang GT 4.6L V8

  6. #6
    Master Mechanic daddytech's Avatar
    Join Date
    Mar 2008
    Portland TN


    Yeah working in car stereo for 10 years installing tuning, building boxes, putting in completely custom audio components throughout the vehicle in some pretty oddly requested places has taught me a few things about this.

    Like a few have said on here already it appears to be a grounding issue. What you are describing is a really high pitched whine that comes from one of the grounds. Typically it's the Amp ground but depending on the type of stereo and how much power it has It can also be caused by the Stereo ground it's self. The stereo it's self used to be the old constant issue. Now for the bad news..... If this issue with the amp blinking on and off like that has been going on for a while it can also be the amp it's self the PAC module you are describing is what old school technicians and installers like myself used to call a stepdown (meaning it stepps the high current from your radio down to low current for the amp it's self) that module if it has a seperate ground (some do) could also be causing the noise. the problem with the amp blinking off and on could be the stepdown it's self or the amp. This is the place where you probably need to start. there are two wires coming from the step down going to the amp they are called RCA cables and are usually Red And White on the ends or red and black and the cable it's self is black. there are some multicolored "RCA cables out now too but the RCA cable will be the "ONLY"one coming from the stepdown (PAC) turn your ignition on and then remove the RCA ends from the amp one at a time.

    I am thinking doing this one at a time the Amp will quit blinking on and off. EX....Unplug the right cable, check the amp, if no change plug it back in and unplug the other one If one side of your cable causes the amp to come on solid and run fine then there is a problem with the side of the amp that is unplugged meaning you can still hear the sound but only through the side that is working properly

    Now then you can unplug the side that is working if that is the case and plug the other wire into that socket if the problem is with the amp then the other speaker should begin working right. if that wire being plugged in to the other side causes your amp to start blinking on and off again however the PAC module is bad and needs replaced (it happens) but also check your ground on the amp and make sure it is securely mounted and still has contact.

    As for the radio noise that sounds like a whine or vibrating squeal that gets louder as the engine revs higher and then settles back down as your motor idles down, that is most often the radio ground that has become unstable. Try Replacing the PAC module first before re-routing the radio ground if the new module does not change anything and the noise persists then the radio ground will need to be re-routed to a solid unpainted frame mount ( steel ) and the issue should be gone
    Note: this is usually only an issue with improperly grounded after market car stereo's not usually the factory units but it's electronics, stuff happens to even the finest of things these days too.

    I know it's kinda wordy but those are the main steps I would take to find someone's issue. If none of those work then it's time to get really technical and pull out the old meter and start testing voltage and such

    OOOH if nothing else and you are really into it you might also check the connection on the speakers inside your speaker box in the back too. one of those could be shorted out as well

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