Ok I need help once again, pretty much done with my audio install but still having a couple of issues that are going to bother me until I can get them resolved.

1) When key is turned to ACC or ON (engine not running) I hear a constant frequency high pitch sound from the engine bay area. The AC and headlights are turned off.

2) With engine turned on or off, when the front doors are opened and volume turned down to 0 on my headunit, there's a slight static/buzzing noise I hear coming from the speakers. Close the door and it goes away. Same thing if I open one of the rear doors but it is much louder.

I don't think it's my amp, as I had the same problem on my old amp and I recently got a new amp and I still have the same problem. I feel that it's either the headunit or some other interference causing it.

When I move the RCAs from the rear channel preouts of the HU to the front channel input of the amp, I get the louder noise on the front speakers with the doors opened. Same thing if I hook up the preouts from the front channel of the HU to the rear channel of the amp, I get the less prominent noise when the rear doors are opened. So basically the noise follows the rca preouts from the headunit.


Here are the details of my setup (sedan w/ factory bose system)

4 gauge power wire running from battery along passenger side to Polk PA 500.4 amp. 8 gauge power wire running from battery along passenger side to Alpine mono amp. Both amps are grounded to a bolt on the cross brace behind the rear seats (perhaps this is a poor ground?).

Speakers are Polk momo 6.5" components up front, running 16 gauge speaker wire to the front components along both sides. Rear speakers are Polk momo coaxials tapped in to the factory speaker wires from the bose amp's connector.

Headunit is a Pioneer AVIC D3, it is connected using the scosche wiring harness I believe. RCA cables from the preouts for all channels (front, rear, sub) are brand new so shouldn't be faulty. The headunit is not grounded through the wiring harness, I grounded it to a bolt in the dash. I have heard of pico fuses blowing on Pioneer units causing lots of ground noise to be introduced through the RCAs but I already checked once and the fuses inside my headunit were not blown.

I'm sure I missed some details but that is the jist of it. With the doors closed and engine running, everything sounds pretty good and I don't hear any noise. Don't get any alternator whine related to rpm when driving or if I do, it's barely audible. Tried searching a lot but couldn't really find anything similar to my problem, I'm thinking the problem is related to bad ground or some sort of interference with the car's electrical systems. I am thinking of doing the big 3 in hopes that it will resolve my issues but if anyone has any other ideas as to the cause, any help would be much appreciated, thanks!

 

So you ran a 4 guage and an 8 guage power wire?

Why not run the 4 guage power to the trunk and then put in a power distribution block and run power wires from that to the amps.

Check your ground. Make sure you have it metal to metal. No paint on the metal surface.

Make sure your RCA's are ran on the opposite side of the car from the power wire.

 

Lol yeah I was going to add a distribution block to the 4 gauge but then I'd need to add fuses to the distro block and upgrade the main the fuse on the 4 gauge so I just found it easier to add another 8 gauge for the mono amp.

The ground for the amp I do need to look in to, I'm not sure if the cross brace on the back of the seats is solid metal or some sort of alloy.

The RCAs I did run on the opposite side of the power wires.

 

bump...wrathernaut where you at lol...what's a good spot in the sedan to ground the amps, I just went around in the trunk and back seat area with my multimeter and I wasn't getting any continuity/resistance across different metal surfaces I tried

 

The seatbelt bolt or the bolts holding the rear seat backs in are pretty hefty-sized bolts which I used to ground 0/1 gauge so you should be fine with that 4 gauge.

Just make sure you sand away any paint around the base where you're connecting your ground.

 

Ok thanks I will try moving my amp grounds there...as for the headunit, did you run the ground back to this same point as well or just grounded it to one of the two bolts that screws in to the bottom of the metal bracket holding the deck.

Also I am not sure if I should also connect the ground from my headunit's power harness to the ground wire on the metra wiring harness and then just ground both of these together or just grounding the hu's wire is fine.

 

if you have your set up pulled from the dash...

try running a temporary set up with new/differernt RCAs, plug them into the head unit and then run the other end of the RCA straight to the amp. Dont run em in the carpet or anything....looks ghetto running straight though the car yes, but its only a test.

try that, if you get dont have noise issues with the new RCAs; either reroute your existing RCAs or buy new RCAs, sometimes RCA cables separate when your pulling them though your interior

I would run to walmart and buy the $5 set to test

 

Thanks for the input, I actually tried that the last time I had the dash apart, I ran a different set of RCA's just on the outside of the car to my amp and it still was doing the weird thing of noise coming from the speakers only when the doors are opened.

That's how I know it's not the RCAs and I also don't think it's the amp because it did the same thing with two different amps and the noise also follows whatever channel I plug in to on the amp.

That leaves me with the HU or something with the car's own electrical wiring. It's weird that it happens with only the doors opened, I mean electrically what would happen in this case to cause noise, the door lights come on and the signal to the dash indicating door is opened...not really sure what else.

I am going to pull the dash out once more and check all connections to the metra wire harness.