Car Stereo Forum banner
1 - 3 of 3 Posts

31 Posts
Discussion Starter · #1 · (Edited)
So, I found out I had a ground loop yesterday! Awesome!

I plugged my iPod into my new charger with a line-out, and heard the popping/revving engine bliss.

This also was the night that I decided to hook up my amplifier to test it out. I heard no ground loop coming through my components. I did not check to see if the ground loop still existed, like a *******. I was told the JL 300/2 has a built in filter - perhaps that's why. Shrug.

I then unhooked the ampifier and unfused the 1/0, back to it's original setup. Ground loop was there this morning driving to work.

So, here is my current situtation:

1/0 gauge wire at the battery, unfused, going to the back of my car to a distro block, one 4 gauge coming out of it (hooked to nothing)

1/0 gauge wire to a bolt in my car, ground down to shiny metal, going to a distro block, one 4 gauge wire coming out of it (hooked to nothing).

So, no wires are currently "live" right now.

I don't want to do anything potentially stupid to try to fix this, but I have a feelilng like my problem is obvious (such as, I have to hook my UNFUSED powerline to my ground distro temporarily until I permanently put my amplifier in).

Just looking for better insight than my own. Thanks.


When I say UNFUSED I meant that the line is fused, but I removed the fuse for the time being to keep the line from being live.

31 Posts
Discussion Starter · #4 ·
Since I haven't been following any threads describing your build, I'm not clear on of what your system consists - or what your last suggestion actually means :)

I hear a lot of talk about ground loop "filters". No such thing. There are ground loop isolators and they can do a decent job, and many amps have a good degree of isolation onboard. (It should be noted that most autosound ground-loop isolators have souch a lousy frequency response that if you hooked one up to an RTA, you would throw it in the river.)

An iPod on a charger in a car often is a noise source. Usually that is a ground loop - but it can also be a charger without power filtering! Cig lighter sockets are famous for having LOUSY grounds, btw.

So I don't know if our iPod is the preamp (driving the amp directly) or is connected to a HU or what, but I would improve the cig lighter ground first, and I MIGHT put a powerline filter in series with the cig lighter power wire (nned a high-amperage one if it ever gets used for a real lighter : )

If the iPod is the preamp, how high is the JL gain? Remember, all systems have noise, it's just inaudible in the good systems :)

If the iPod is connected to the HU, I guess I would take the cig lighter ground and re-route it to the HU ground (the HU ground in my installs would have already been run to the amp ground).

BTW, if I recall correctly, the iPod preamp out can't really drive a Jensen Iso-Link well (best ground-look isolator on the market). Markertek also has a cheaper one that tests pretty well. (Rolls?)
Let me clarify my current setup:

- An Eclipse CD8443 Head unit
- Wires to hook up an Amplifier

That's it.

To further specify my wiring setup, I have a wire from the battery to my spare tire, and a 1-2 foot ground wire hooked to a bolt in my wheel well

Other than that, everything is stock. No amps, no alternate speakers, nothing. I'm going to be putting in all of my stuff this summer.

I've taken the fuse out of the power wire, to keep it from being a live wire.

So essentially, there's just a wire chilling under the hood, routed through my car, and ending in the wheel well.

I'm curious if just having this wire hanging out under the hood can cause a ground loop, since it's not hooked to anything, and if it's safe to link my loose power wire to the ground cable for the time being (or if there is a 0% chance of that doing anything at all).

Like you said, it may just be that the cigarette lighter outlets have ****ty grounds, and I have to re-ground it (to my head unit ground preferably).

If my iPod is unhooked from the charger, the ground loop is gone (obviously).

So, is it OK to "ground" my wire that's hanging out under the hood with the fuse taken out? Would that... COULD that even be a problem?

31 Posts
Discussion Starter · #5 ·
OK - So I did a bit more research on a forum specific to my car (Mazda 3) and pretty much ALL Mazda 3's have this issue. There's thread after thread of people reviewing ground loop "isolators" (I put it in quotes) and whatnot. Everyone says to ground the cigarette lighter to my stereo's ground as being the best fix - I think I'll go this route.

So, I locate the ground wire, and splice it into my wiring harness ground for my stereo - correct?

Just for the sake of asking, if I were to plug in my cigarette lighter after doing this fix-up, would bad things happen? That's a lot of current.
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.