Bruce In Philly

2009 C2S 100K miles

Anyone installed an aftermarket system and dealt with alternator whine in our cars? Help please. A better way to test the alternator than what I did below?

I had the head unit and amp swapped out about three weeks ago and back four times and they can't get rid of the alternator whine. The installer is highly reputable, been in business for 30 years, and they are stumped. They are thinking it is my alternator. I just checked the alternator up as Sunoco station, they said it was "perfect" and I just tested for AC ripple/leakage by putting my Fluke on the battery terminals and it came out way below spec.... like .05 volt... Fluke says .5 AC volt is normal. I could not get the Fluke onto the positive terminal on the alternator as the plug is in the back of the thing.

So I took a half a day and we went driving, the installer with the Alpine unit on his lap and one by one, we unplugged the radio antenna, XM unit, microphone, GPS antenna, woofer cable. Nothing, no effect. Then keeping this stuff unplugged, we stopped the car and started pulling speaker cables from the amp in the trunk. One by one, had to leave one connected to hear, and no effect. He was pulling power from a CAN cable, so he moved it to the fuse box, again no effect, then put a filter on the power line, no effect. Weird.

There is more to this story. First, I wanted the amp where the Bose amp was, under the passenger seat.... no re-running of cables.... but due to the small space, I had to use an expensive Mosconi amp... not happy about this Mosconi, but that is another story. Got Whine. They throught they did everything by re-routing cables in the dash, swapped out the head unit for another.... and even put transformers on the analog lines.... something I DON"T WANT. They unplugged the airbag module under the seat and they thought that did it. So.... we dumped the Mosconi and went with a JL amp I really wanted and put it up in the trunk. So the speaker lines had to be extended from under the seat out to the front trunk.

So... after all of this.... still alternator whine. The whine varies with RPM, is not effected by volume. The one thing we did not do is put a big cap on the battery.... I am not sure I want to do that as I don't want to mitigate, I want to stop the whine.

Like I noted above, they are starting to blame the alternator but I am skeptical because of my tests. Oh, there was no whine with the Bose system. And I had swapped out my speakers for Focal units last summer and never had whine.

Peace
Bruce in Philly

slicky rick

Bring out the cheese Bruce. Seriously though, that's one tough cookie to get rid of. You have tried most everything. Good luck partner.

MemeMagno

Hey Bruce...I didn't have time to start with my project, but I will keep you updated. One thing that I will do is grounded the the Amp. directly to the battery (w/ fuse box), but the HU grounded with the original harness (Plan B to a source without alternator whine...). Did you try to find a second opinion in another Audio shop? How good are the Amp cables from the wiring kit...4 GA or less? And the RCAs?
Cheers,
T.

ru'

Have you tried a different HU or amp? It's possible the internal power feed filtering may be fried?

Bruce In Philly

Thanx for the tips Tristan, the installer tried using larger gauge wires and tried another grounding source. I don't believe we went straight to the battery for everything.... that is something I want to try next. I take the car back to him on Wednesday.... I suspect I will be getting the car back with the original system. He did use two different sources of power... a source in the CAN cabling (?), and direct to the fuse box.

Ru' we tried two different amps located in two different places... a Mosconi under the passenger seat and a JL in the front trunk..... same.

Peace
Bruce in Philly

ru'

Is the noise there with the amp disconnected from the HU (I'm assuming it's RCAs from HU to Amp)?

If the noise stops, does it come back when the RCAs are connected to the amp but disconnected at the HU end?

Is the HU and amp grounded at the same place?

Noises like this can drive you mad!

mreloc

I've found this to be a big help in eliminating whine, bu it can be a biatch... main reason I am satisfied with the factory Bose system... for now

MemeMagno

Bruce,
Before to go back to stock, try the Amp. connected directly to the Battery (which at the same time is a big capacitor). For the HU: Move the ground to the chassis/ subframe. With my installer we decided to not re-use the OEM harness in order to avoid whine noises.