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?

 

Its definately a ground issue

 

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

 

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.

 

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

 

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.

 

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.

 

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.

 

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.

 

You got a guy who doesn't know ****. 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?

 

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.

 

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?

 

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 ****ed 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?

 

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.

 

Not having the AMPS would really take away from what an awesome system the 460 is, so I'm going to try to solder rca plugs up to the speaker wires and plug it in like that. If that doesn't work i'll try grounding it from the amps, etc.

Luckily I purchased the deck from best buy and I'm pretty sure they will take just about everything back as long as I have the box. With that being said, would I have a better chance of everything working if I get a deck with more watts?

 

I don't if this matters, but right now everything on the stereo funtions normally, I can still crank it up really loud with no problems. The only problem is the loud ass HUM in the back ground, which does NOT get louder as my music gets louder.

 

Alright so My friend, who is a bit more electrical savvy, says I have a postive loop. He said when the positives are disconnected there is no sound. We also unhooked the amps completely and that didn't change a thing. RCA plugs didn't help in the least bit, and everyone is a little more frusterated lol.

Another discovery, the HUM is the worst while at idle. If I'm cruising down the highway at 1700 RPM, there is no hum what so ever.

 

Lol, when you disconnect the positive, the speaker can't play anything so there won't be a hum. When you're cruising at 1700 RPM, I'll bet the hum is still there. Generally engine noise, which is alternator whine, will increase in pitch with RPM. The higher the pitch, the less you can actually hear and most likely by that RPM it's at such a high pitch that your ears can't actually detect it.

When you say you unhooked the amps completely and it didn't change, what do you mean? You unplugged them and you still had the whine? Because that's not possible, so you must not have been unplugging the actual amps if that was the case. Or if you just unplugged the inputs and had the amps still powered and the speakers still hooked up, then the problem is with your amps themselves.. I was going to suggest that next, to disconnect the deck, power the amps and see if the noise was still there, that way you can start to isolate the issue.

 

Maybe he said he disconnected the negatives, I might have gotten that switched around.

Yeah I definitely just unhooked the inputs. I unhooked the power now and the hum is gone...along with the back speakers of course.

Would a ground from the amp help? Or even, new amps?

 

Ok! So I unplugged both amps and the HUM was gone. I plugged the amp to the front speakers back up, and there was no HUM. I unplugged the front amp and plugged the rear back in and the HUM was back.

I'm going to switch the amps around and if the hum is gone, then I obviously shorted something and just need a new amp. I HOPE I HOPE!

 

Can't remember but did you try running a fat ground no more then a foot long directly to the body.

 

I didn't actually. Which is the ground on the amp?

 

I'm referring to the amp that hums

 

Didn't read much of this but will say a lot of times the engine noise comes from power and rca's being run to close.... It always cracks me up when someone gets a "professional" instal and they run all the wires and rca's together and even tape them together.....

 

Lol. I've seen that to

 

Not sure on a stock amp

 

I'm looking at schematics from ALL DATA and they don't show a ground from the amp.

Maybe I can try grounding out the power? Hmm, I think tomorrow I'm going to rip the amp out and open it up, maybe I can find some burnt out solder or something.

 

I have a similar problem...but, my Hum is one pitch and my head unit is completely disconnected...riddle me that one...

 

On my car it's a fat red wire. Not sure if it's the same for you. I'm guessing it will be the biggest gauge wire in the amps harness. I guess you could try unplugging the amp and check the harness on the car side to see which wire is ground my using a multi meter. Hold one lead to cars body and then check each wire on till it shows shorted. Then you'll know which one is ground ,follow that to the matching wire on the amp plug. There maybe an easier way of finding ground but that's the best I can think of right now

 

Nah, that sounds plenty easy.