[Sinatra]

Wow, I'm so damn confused...

Yesterday I noticed my driver headlight was flickering off and on. The problem was a loose ground wire from the battery. I took out the stock bolt and screwed them down with a bigger one.

Problem fixed, the light is strong. NOW though, a VERY loud static hum is coming out of all my speakers. When I rev the engine the hum gets faster and more high pitch, when it idles the hum is slow and low. If I turn the stereo on while the car is not running, there is no hum at all.

I am totally blank on this, any ideas?

[69fastback]

Does it have aftermarket stereo stuff in it?

[shamrock81887]

Its definately a ground issue

[Sinatra]

Originally Posted by 69fastback Does it have aftermarket stereo stuff in it?

Its a totally stock 460, the only thing new is the deck.

Could it be the coating on the screw thats throwing it?

[shamrock81887]

I had this issue i fixed it with a ground loop isolator but mine was coming out my subwoofers id just check all the wiring maybe even change the ground from the stereo and mount it somewhere else

[shamrock81887]

The coating on the screw thing maybe any things related to the ground is worth a shot its definately your ground i think what your experiencing is called a ground loop

[Sinatra]

Originally Posted by shamrock81887 The coating on the screw thing maybe any things related to the ground is worth a shot its definately your ground i think what your experiencing is called a ground loop

After looking up Ground Loop I think I have a couple of solutions in mind. I do have two grounds in generally the same place. Thanks, i'll trial and error some things.

[fogged306]

Ground the battery and the engine to the same point on the frame. If that doesn't work, try running the radio ground out to that point also. Like mentioned above, it's a ground loop.

[Sinatra]

Originally Posted by fogged306 Ground the battery and the engine to the same point on the frame. If that doesn't work, try running the radio ground out to that point also. Like mentioned above, it's a ground loop.

They have always been grounded at the same point, i thought I would try separating them

[fogged306]

Then pull them off and sand everything down to bare metal and re-attach. Grounding them at separate points is what can cause a ground loop. Make sure the alternator is getting a solid ground through the case also, that is the source of your noise and why it changes with RPM. Somewhere you're getting feedback in your grounding system. Could also be a faulty deck. If you were having grounding issues to begin with, I could have damaged it. Older pioneers are notorious for this.

[ryanw]

Originally Posted by fogged306 Ground the battery and the engine to the same point on the frame. If that doesn't work, try running the radio ground out to that point also. Like mentioned above, it's a ground loop.

plus 1

[Sinatra]

Tried switching the ground from the deck (which is brand new), no difference.

How do ground loop isolators work?

Grrr now I have to listen to the high pitch chirp of the brand new throw out bearing.

[Sinatra]

Tried a ground loop isolator and it didn't do a thing. I took it to an audio shop and they said the stock Mach systems don't work well with after market decks and it's the deck thats causing the hum.

If the deck wasn't compatible wouldn't it have not worked well when it was first installed, not months afterward?

The guy said it's either my alternator going bad or I need to replace the aftermarket stereo with a stock Mach 460 one.

Any ideas? It seems like a bit a BS to me.

[Sinatra]

Did I mention that before I debunked his electronic, in my face, sales crap he said my entire stereo was bad and I needed all new speakers.

[fogged306]

You got a guy who doesn't know shit. I worked for stereo shops for the past 12 yrs of my life and now I own my own shop. If it worked fine and stopped, it has nothing to do with your stereo and the mach system not playing nice. I will agree that it is a pain in the ass to get that combination to work well together, but if it worked once and then stopped, then it's a part issue or poor ground somewhere. How is the deck wired in to the mach system, with a low level harness? Should be RCA's coming from the deck to the harness if I remember right. What deck do you have and how many pre-outs does it have?

[Sinatra]

It is a KD R520. It has 4 RCA jacks in the back. 2 say Front R & L, the others say Rear/SW R & L. I don't have anything plugged into those Jacks.

I Chopped the factory harness, matched the wires, solder and plugged the decks harness in.

[ryanw]

monster cables with the built in ground work great...not the cheap ones ( the big fat one)

sand paint off and ground any deck, amps ect.. real good with a good size ground wire. I could have told you that ground loop isolators wouldnt work

[Sinatra]

Originally Posted by ryanw monster cables with the built in ground work great...not the cheap ones ( the big fat one) sand paint off and ground any deck, amps ect.. real good with a good size ground wire. I could have told you that ground loop isolators wouldnt work

I sanded off everything and pulled the ground from the deck up to the Engine Ground, no difference.

The guy at the shop said its definitely not a ground issue, he said its an issue with the deck and the stock system. Any validity to this?

Is it possible that my method of connection was always wrong and is just catching up to it now?

[fogged306]

I'll have to check my book when I get to the shop monday but I'm pretty sure those use a low level harness. Running speaker wires from your deck into that could have fucked up the amps in the 460 system... Not 100% on this until I see what the harness is supposed to be. It is possible that with the car having a poor ground somewhere it could have masked the issue, or it could be that fixing that was the final straw and something blew in the amp(s).. Or it could be a grounding issue. If that guy tells you engine noise has nothing to do with ground, never go to that stereo shop again. Yes it could very well be an interfacing issue, but to discount it being a ground problem is just plain lack of experience.

Is this a 94 or a 95?

[fogged306]

Forgot the company that makes harnesses has an online page, just looked it up.. You're above the threshold for being able to wire speaker wire to the 460s amps inputs. Says 35W and below per channel decks can wire high level and anything above, you need to switch to the RCA harness. In your case, since you cut it off, you can either solder RCA ends back on to those wires and run it like that, or you can just bypass the factory amps completely. The problem with engine noise is that it can be a nightmare to track down sometimes, and switching your harness around is no guarantee that it will eliminate the noise. Bypassing your amps will work 99 times out of a 100 because the ground loop is almost always created when you run an amp separate from the deck. Keep it all internal and you have almost no chance for noise. Your stereo won't be as loud as it is now if you bypass that system though. You can also try running a small ground wire from the amp ground to the radio ground. Or from amp casing to radio casing and different combinations of those two suggestions. Sometimes it's a lot of trial and error.