proper ground?

I read through the gounding page and didn't find an answer so here is my question.

I have a slight alternator whine that I can not seem to cure. I am certain it is not coming from my audio cables so I think it must be the ground. Attached is how I have the system grounded. I added the 10ga wire to try and cure the noise but it didn't have any impact. I am curious though if I should not be grounding to the bolts in addition to having the wire run from the battery.  My power source to the PC is a 12ga wire. This in a Nissan Armada so the PC is about 16 feet away from the battery.  Should I just tie the individual components to the ground wire and not connect it to the vehicle body?

Here is a link to my installed system...I doubt if there is any useful info in them that would help diagnose the system but I'm proud of it so I'll add the link anyway

I had the noise before I added the 10 gauge wire. I added the wire hoping to get rid of the ground loop. What I'm wondering is if when grounding directly to the battery I should remove the chassis ground points? If I'm feeding power with 12ga I assumed a 10ga return line was sufficient plus it is in addition to the chassis.

The .5 ohm's, is that measured between the battery and the ground point or the ground point and the equipment?

First, I followed your link and must say, I am impressed.  That's a pretty awesome setup, and now I hate you for getting my gears spinning inside my head .  Just kidding.  If you got all that stuff figured out, I'm sure you can figure this out.  Start with the basics:

Your power and ground wires should be the same size.  Once you figure the current draw of your system, you can select the proper size wire.  You can use these charts as a guide: https://www.the12volt.com/info/recwirsz.asp.  This will help ensure you have minimal voltage drop.  Next, make your ground wire as short as possible, and connect it directly to the frame/body of the vehicle, not the battery.  If it's impractical to ground all your equipment at the same point, you can use seperate grounding points, just make sure they're clean and secure.

If this does not clear up your noise issues, do some trouble shooting to isolate the problem.  You might try bypassing the a/v switcher first and see if that clears it up.  I'm assuming the noise is on all sources, that's why I suggested this.  You can also try connecting grounding all signal grounds to a common point.

Okay I took out the 10ga wire and checked the grounds with an ohm meter....but I think I need to redo it as I didn't understand how to read the meter so I set it on 2k and was reading .003. What I did was ran a wire from the battery ground and hooked one probe to it and touched the ground point with the other probe. I also put the probe on the other end of the ground wire that is hooked to the ground point and got the same reading. I did the same thing at the ground for the AV switcher and it read .001-.002. (oh and I tested the jumper wire by itself and it read .000)

I think I now understand the settings for the ohm meter and should of had it set on the 200?? I thought since there was three digits right of the decimal that the 2k was reading smaller values...not right..right? this is the meter I have http://www.professionalequipment.com/xq/ASP/ProductID.1776/id.9/subID.102/qx/default.htm

I need to run the wire to the battery again to retest the ground points but when set on 200 I get 00.5 testing from the ground point to the other end of the wire going from the PC to the ground. Was my .003 reading between the battery and ground point really 6ohm? If so is that too much? Is the .001-.002 difference between the PC ground and the Avswitcher ground points too much? With these ground readings I still have the whine. Im going to try and bypass the avswitcher audio tomorrow and see what happens. I think I've already done this but can't remember for sure.

Thanks for the help.

I just skimmed through your link, and first gotta say that's pretty sweet.  Second, I think that I read that you have some type of power inverter hooked up for your pc, is this correct?  If so you may be getting some noise from that.  Also where are you getting the power from those fans?  That could also be introducing noise into your system.  Don't know if this is any help, or if you've already tried this, but I thought I'd post, just in case.  I know how when you're racking your brain on something for a long time, you some times over look something simple.  Good luck and keep us all posted.

ps If nothing  you try seems to work, try getting a simple power noise filter.

Thanks for all the suggestions.

The power inverter isn't your normal $20 walmart special. Its specially made for carputers. I've checked the fans before and unplugged them and there is no difference.

Well I redid all of the grounds and am confident there is no way I can get them any better...not saying someone else couldn't. Anyway I tested the ground from the battery to both the computer and the other pieces under the front seat. the ohms were 0.02 at the PC and it bounced between 0.02-0.03 up front. When I bypass the amps and avswitcher it is dead silent playing from the PC with no ground loop isolator. but when I run through either the avswitcher or the amps there is noise. It's about the same individually as it is with both hooked up. I went and bought a power line filter and it made maybe a little difference but not much. I was doing all of this with the ground loop isolator removed and after I gave up I noticed the audio sounding crappy. The highs were good but everything else sucked. I played around for awile and finally put the ground loop isolator back on and it fixed it. The whine is a lot less noticable....so I'm calling it good. I'd really of liked to of not used the groundloop isolator but I give up trying to figure out what is out of whack. Thanks again guys for the replies.