Alternator whine BMW pt.2

[Karuza]

Tests done;

1. Hooked up new RCAs to HU and amp

2. Test ground on amp (Ground is hooked up to negative terminal of battery. People have different views on this but this set up worked previously before the alternator whine came about, would it be recommended to ground to bare metal?)

3. Hooked up RCAs to amp and touched bare metal (whine is there when touches metal)

4. Turned sound completely off on HU (Whine goes away)

5. Disconnected the 2 door speakers that had whine (whine goes away)

6. Hooked up jumpers to other car to test alternator, alternator is fine whine is still present, but is not present in the good car.

I think my door speakers went out or my amp went out.

What do you guys think?

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[Supergumby5000 5,000+ posts]

if the whine fluxuates with the volume of the headunit, its most likely an equipment problem.

ground the RCA's to the back of the headunit and see if that helps.

It could be the amp, but i would suspect the headunit before that.

 

[Supergumby5000 5,000+ posts]

have you swapped out the RCAs themselves? thats a really common issue, and didnt notice that in your first post.

 

[Karuza]

Test #3 shows it has nothing to do with head unit.

Test 3 shows the RCA connected to the amp, with other end of the RCAs touching bare metal still getting alternator whine. The HU was not connected to the RCA

Test #1 New RCAs were purchased and test and still receive whine

 

[Supergumby5000 5,000+ posts]

Test #3 shows it has nothing to do with head unit.
Test 3 shows the RCA connected to the amp, with other end of the RCAs touching bare metal still getting alternator whine. The HU was not connected to the RCA

New RCAs were purchased and test and still receive whine

sounds like you know exactly what the problem then is. got a buddy with an amp you can swap in and test?

 

[Karuza]

The gnd from the amp is hooked to negative terminal on battery, although this has worked fine before, do you think it could be the culprit to the problem? Should I ground it to bare metal?

Not that I know of, but I'll ask around.

 

[Supergumby5000 5,000+ posts]

The gnd from the amp is hooked to negative terminal on battery, although this has worked fine before, do you think it could be the culprit to the problem? Should I ground it to bare metal?
Not that I know of, but I'll ask around.

Shouldnt be an issue. If anything, thats going to have less resistance than grounding to the chassis/frame. That type of issue would create a ground loop though, and the whine probably wouldnt fluxuate with the volume on the headunit, but rather always be there.

I ground to my batteries.

 

[Karuza]

It doesn't go up or down with volume of head unit, it only goes away when volume is 0, I'm assuming the head unit stops sending out a signal at this point. Also, its only my door speakers, and not the other speakers in my car

 

[infamous_e46 5,000+ posts]

Had the same problem right before my battery died completely //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[Karuza]

Brand new optima battery

 

[Supergumby5000 5,000+ posts]

It doesn't go up or down with volume of head unit, it only goes away when volume is 0, I'm assuming the head unit stops sending out a signal at this point. Also, its only my door speakers, and not the other speakers in my car

i would test a different amp then. Im thinking its the amp, doesnt sound like a wiring issue.

I had a similar issue with an amp, and turned out that the amp had a bad power supply