can’t get rid of alternator whine

I recently installed a Pioneer Avic D3 and have been having bad alternator whine (or a ground loop). I'm really stuck on this and want to see if maybe I missed something.

I'm going to give a little back story incase it helps in figuring this out. I installed two subs and an amp in my car which caused me to get alternator whine. To supply the amp I tapped the line outs from my factory headunit. To fix the whine problem I connected the common ground (the headunit has four speakers positives and one speaker negative) to the back of the oem headunit. I later had the oem headunit replaced for another issue and the new unit still had the same noise problem.

Now I installed my Avic D3 and the noise is back. I started by completely unhooking the subs from my car as if they were not even there. That did not help. The next thing I did was to fix the oem wires that are behind the radio. Long story short: they were a bit hacked up from the sub install. I cut, spliced, and soldered in new wire (with head shrink), which did nothing. I then took out the harness that goes from my OEM wires to the Avic D3. I made sure all the connections were good and only hooked up the bare necessities to see if that would help. To further confuse me, one of my solder connections came loose so only that speaker's negative is hooked up. This speaker gives really bad noise now (louder than the other speakers).

The car has a factory (bose) amp so maybe that is where the noise is coming from. I tired grounding the outside of the headunit to the car, to the rcas, to itself, to the common ground, etc and nothing worked. It was suggested that I don't run the headunits power wires next to the speaker connections (behind the dash). I have to check this, but I don't think that's causing this. I was also told not to use the OEM ground wire and just ground the headunit to the chassis. Another suggestions is to find a new accessory wire (I'm using the PAC SWI-CAN which provides the accessory wire as my car does not have an OEM one). Is there anything else I can check? I read that the Pioneers have a fuse in them that can go bad and cause this, is there some way to check this?

Thanks for your help - It's just driving my crazy.

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Owner
SFV AutoSound

Pioneer's have an inherent ground plane problem that has plagued all the Pioneer HU's. The only thing you can really do is replace the HU with another HU to ensure that it's not the AVIC or replace any RCA wires one at a time to see if you have problems with your RCA's.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

Velocity Motors wrote:

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Pioneer's have an inherent ground plane problem that has plagued all the Pioneer HU's. The only thing you can really do is replace the HU with another HU to ensure that it's not the AVIC or replace any RCA wires one at a time to see if you have problems with your RCA's.

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Would I be able to test the headunit by running the rcas to a home stereo in my garage (it takes RCA input)?

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Owner
SFV AutoSound

I've been back and forth on a few Pioneers with the ground fuse problem, and it sounds like you already checked what you need to, but just in case, here's the procedure:

Grab a foot or two of relatively small wire (18AWG will be fine) and ground one end to a good solid spot on the chassis. Take the other end and connect it to the outer shell on the D3's RCAs. When I was testing mine I just stripped the end off an inch or so and held it to the barrels with a clothes pin. If the whine goes away, the little picofuse on the board inside that connects the RCA ground to the internal ground is hosed, and you need to either replace it or exchange the HU.

Good luck.

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This is not a sig. This is a duck. Quack.

Maybe I am reading this wrong but you had a noise problem prior to installing the pioneer, correct?

Just out of curiosity what vehicle is it?

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dpaton wrote:

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I've been back and forth on a few Pioneers with the ground fuse problem, and it sounds like you already checked what you need to, but just in case, here's the procedure:

Grab a foot or two of relatively small wire (18AWG will be fine) and ground one end to a good solid spot on the chassis. Take the other end and connect it to the outer shell on the D3's RCAs. When I was testing mine I just stripped the end off an inch or so and held it to the barrels with a clothes pin. If the whine goes away, the little picofuse on the board inside that connects the RCA ground to the internal ground is hosed, and you need to either replace it or exchange the HU.

Good luck.

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Cool thanks. I think I tired that, but maybe I did it wrong. Should it be touching all of the RCAs at once?

xtremej wrote:

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Maybe I am reading this wrong but you had a noise problem prior to installing the pioneer, correct?

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Yes I did, I was able to get it to go away by grounding the common speaker negative to the back of the factory headunit.

dwarren wrote:

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Just out of curiosity what vehicle is it?

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Duh... that would have probably been a good thing to include in my OP. Sorry, it's an 04 Audi A4 with the Bose sound system.

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Owner
SFV AutoSound

You're not trying to use any of the Bose gear are you?

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Support the12volt.com

DYohn] wrote:

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You're not trying to use any of the Bose gear are you?

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Yep. Linelevel out from Avic D3 to linelevel in on Bose amp. Why?


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Owner
SFV AutoSound

SFVautosound wrote:

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DYohn] wrote:

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You're not trying to use any of the Bose gear are you?

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Yep. Linelevel out from Avic D3 to linelevel in on Bose amp. Why?

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Because that's probably the source of the noise: a ground loop between the HU and the Bose amp.  Get rid of the amp and see what happens.

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Support the12volt.com

DYohn] wrote:

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SFVautosound wrote:

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DYohn] wrote:

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You're not trying to use any of the Bose gear are you?

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Yep. Linelevel out from Avic D3 to linelevel in on Bose amp. Why?

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Because that's probably the source of the noise: a ground loop between the HU and the Bose amp.  Get rid of the amp and see what happens.

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Ok, I figured it might be that. I fixed the broken wire today (temporarily) and the whine is mostly gone, I have to do some better testing (went to the track today) to see if I can hear it anymore. As to bypassing the bose amp...I probably have to make my own bypass cable, correct?

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Owner
SFV AutoSound