Ground Loop

captain_fink · Post by **captain_fink** » Wed Jul 20, 2005 9:42 pm

Just installed the HU(Eclipse 3422) into my new truck. The HU works fine, great sound, no buzz. Installed XM with the HU(direct connected through the AUX input on the back, powered through the cigarette lighter plugin), but there's a buzz in the background (even when the XM is turned off but still plugged in, but only if the engine is running). I didn't think it was ground loop at first(loose wire or something, but they're all fully connected), but tonight when i got in to drive home from work I noticed it changed pitch with the engine RPM's. So now I'm assuming its a ground loop. So to fix it basically I need to make the deck and the XM have an equivalent ground. Can I move my ground from the factory harness to a clear metal spot behind the dash near where the PowerPoint is? Or can I just add a wire to the factory ground and ground that to the dash? I'm assuming the HU has a better ground than the power adapter, is there a way to better ground the PowerPoint?

And I'm assuming ground loop is 2 electrical devices with individual power and ground where one device doesn't have as good a ground as the second, so you get a bit of current across the connection to the better ground?

Long post, lots of questions.... Kiki this is made for you.

JeremyC · Post by **JeremyC** » Thu Jul 21, 2005 12:18 am

If you can, go direct with the XM conecter, and get rid of that cigarette lighter plug. I That may be part of your problem. As for the eclipse, just run a completly new wire to a ground point, or a peice of metal under your dash. You can even check with a test light or ohm meter to make sure you have a good ground.

As for the XM, cut off the conector, add in an inline fuse, and find a wire that it hot with the ignition on, and then run a new ground. It very possiable that the XM isn't making a good ground inside the cigarette lighter, and that is were your problem is comming from.

Post by **GlassWolf** » Thu Jul 21, 2005 7:38 am

yup hardwire it all. lose the lighter plug adapter. those things are notorious for noise introduction.
ground directly to metal, and use a switched power line from the fuse box or at the radio harness for power

captain_fink · Post by **captain_fink** » Thu Jul 21, 2005 10:00 am

I would... I'd like that alot better, but it switches down to 6v, so I can't wire it straight in. I'll check the ground on the factory harness, and see if i can ground the adapter any better.

JeremyC · Post by **JeremyC** » Thu Jul 21, 2005 2:50 pm

If you can pull the plug apart, remove the step down and wire the 12 volt plus strait to it. You will want to make something to put it in, or just use the cigarett lighter housing with a positive and a ground comming out of it. Wount look to spiffy, but if you hide it in the dash no one will ever know.

captain_fink · Post by **captain_fink** » Thu Jul 21, 2005 7:21 pm

I'll check it out. It comes apart for the fuse, so I should be able to remove the spring loaded contact button and wire it all up. Might pull the fuse out and put an inline so I've got more room inside the housing. To eliminate the buzz I should just splice a second wire off the switched power and the ground wire my HU is using, right?

JeremyC · Post by **JeremyC** » Fri Jul 22, 2005 9:50 am

You could tie into the headunit turn on lead, and it probably won't hurt anything, but I would try to find something else to tie into if possiable. As for the ground, go directly to metal. It will only take a few min longer to do, and will keep you from having to go back and redo the ground later if the whine is still there.

The inline fuse thing, sounds like a good idea, and that is what I would do.

captain_fink · Post by **captain_fink** » Sat Jul 23, 2005 7:25 pm

It's all wired in, and the buzz is very faint now. I'll live with it for now. When it really starts to bug me I'll pull the HU and wire both the HU and the XM receiver to metal (like I should have done in the first place).

But I'm not sure its the receiver, I think it might be from the stupid 12v to 6v converter. Why Delphi didn't make the stupid thing 12v I will never know.

JeremyC · Post by **JeremyC** » Sat Jul 23, 2005 7:44 pm

Cause then you wouldn't have to pay for their damn adapter.

captain_fink · Post by **captain_fink** » Sat Jul 23, 2005 7:50 pm

lol the adapter comes in the 'car kit' which includes the antenna and base unit. But I guess they couldn't try retailing it for $50 if it was only two pieces.