Alternator Whine

[Azlandshark]

I know this may have been addressed, but I did a search and did not get much so here it goes.

I just re did the audio system in my charger and as with most american cars I have worked on, I get the dreaded alternator whine. I checked the ground at the HU and it is secure with a 4.2ohm resistance. This should be acceptable. I then checked the amplifier grounds, initially I got 138-160ohm reading, so I moved the grounds to a different location and now I get roughly 8ohms, this should be acceptable as well.

The one thing I did notice, I cut the ground at the harness, and never lost power to the deck. I removed the antenna cable from the HU and that shut it off. I also found that if I wiggle the antenna lead coming from the HU, it does cause the deck to flicker on/off. I think this might be the culprit. The other thing I think might be an issue is the crappy RCA cables I am using. I will purchase 2 more sets of a twisted pair and try that.

I did try to move the ground of the HU to another locaion and got no result as well, and still end up with a roughly 4ohm resistance.

FYI my system consists of RF amps, Clarion HU, and all Polk Momo series speakers. I am running 4ga wire to each amp, grounded by 4ga wire as well. Each amp has its own run of B+.

Any thoughts, suggestions, would be great. I haven't installed for over 8 yrs, and I used to be the go to guy for getting rid of noise. This one is trumping my knowledge pool. Please help and thank you in advance.

[BrlntBlackSE]

Assuming you have the power wires and signal wires seperated and not running parallel to each other.

Even with the main ground cut at the HU you still have a few paths to ground i.e. the antenna, the rca shield, etc. Try grounding the chassis of the HU in addition to the ground wire.

What interface did you use to install the Head Unit (hope not metra seen tons of other issues with the metra piece not noise but still)

Make sure your RCAs are good quality.Replace them 1 at a time temporarily first without going to all the trouble of routing them permanent until you see if this fixes it.

Where did you ground the amplifiers. Are they all under 1 screw, in a distribution block, or did you seperate them and do them in a row leaving 1/2 inch in between them. Also did you take the grounding point down to bare metal? How long are the grounds as short as possible is best. Are your ring terminals you used on the grond wire all SOLID connections? Soldered if at all possible with that 4 gauge.

Assuming everything until now is not fixing it. Are the amplifiers mounted directly to the floorpan or any other metal part of the body of the car? If so does unmounting the amplifier make the sound go away. Ive seen this in tons of RF and Kicker Amps.

This wouldn't cause your noise if you didnt do it but did you replace the small factory ground cable in the trunk to the battery with at least a 4 gauge? If you did are those connections solid?

Once you eliminate all of the accessories and the installation then you have to start suspecting the equipment and start checking one at a time.

[SPguy82]

I get noise from the main harness running up the passenger side. I have my right side crossovers over top of the harness, and even with the radio off and the wires disconnected from the amp it causes whine to come through the right side speakers, pick up the false floor and the noise goes away, lower it down and it comes back. I plan on wrapping that big harness and factory power wire with mu metal foil hoping it will shield it.

[Azlandshark]

I tried to ground the HU chassis as well as the radio harness which resulted in nothing. the amps are not mounted to the floor, they are mounted to MDF which is secured in place by fit of the MDF to the car (trust me it wont move). The amp grounds are as short as possible and are secured to bare metal (paint removed with sandpaper). The amps are grounded under one screw. I am going to try running atemp ground directly to the batter and to the mid/high's amp to see what happens there. I did go out and purchase 2 sets of twisted pair shielded RCA's, which I think might be the culprit. After speaking with Tech support, there might be an issue with the amp since when I disconnect the RCA's at the amp, I get a warbling sound from the cabin speakers. After I try the new RCA's and regrounding again, I will contact tech support and see if I can send the amp in for testing. I would be willing to drive it straigh to RF if they would let me.

I did not repalce the tiny factory ground in the trunk. I looked at that and said WTF why did they use such a small ground and large power wire. That doesn't make sense to me, but then again Im not a Chrysler engineer. I will probably repalce that ground as well in due time.
Thanks for the advice, I will keep working at this....

[Gonin60]

What year is your charger? I'm having the same issues with a ground loop that I can't track down. Which head unit do you have?

[Azlandshark]

I have an 07. I think I may have isolated the problem. While I was playing around with the new RCA's, I fuond that I can make the sound louder or softer by moving the RCA pre-out wires from the deck. I found that the front pre-out is the one that is causing the noise level to rise and fall. I also found that if I ground directly to the battery, the sound decreases a little bit. I will end up grounding the amps to the battery as soon as I make their permenant home. The noide has dissipated quite a bit with the new rca's and the pre-out well taped to hold its position.

I have a clarion VRX765vd or something to that effect. Its an in dash DVD player that slides out. I am in the process of trying to find a new HU as this one is crap, and I am thinking about dropping in a double din unit since there appears to be enough room. I will have to either modify the bezel or buy the one for the nav unit. Either way im getting somethign differen't.

[Motor]

i just drop it lower in gear and pound the gas pedal...car screaming covers up the whine:D

[the727kid]

Wrap a piece of un shielded wire rounds the metal part of the RCAs and then secure the other end of the wire to the headunit chasis, should fix the problem.