AgRunner06

I've got an intermittent whining engine noise in my driver side rear speaker in the cargo area under the window. What causes this? It seems to come and go without much reason. I've got an amp and sub back there. The power wire for the amp runs along the doors under the carpet. BUT the amp isn't on because I pulled the fuse. I thought that may have been the problem but it's not.

Any ideas?

Thanks

:bounce2:

AW1090

Maybe this will help a little

https://www.yotatech.com/forums/f96/stereo-whining-noise-during-accel-46950/

midiwall

You're hearing noise that's being picked up through "induction". Crutchfield has a nice troubleshooting chart that can help (and of course will sell you the product needed to fix it ):

http://www.crutchfieldadvisor.com/IS...car/noise.html

96LtdYota

interesting... thanks

AgRunner06

Ok so I'm guessing it's a grounding issue. Is it correct to assume that the problem is the ground for that one speaker (not the sub)? The noise doesn't come out of any of the other speakers so that would lead me to eliminate the deck. Anyone else have any other insight as to where I should start looking for the problem?

midiwall

There's no "ground" per se' at the speaker. While a a speaker accepts a "+" and "-" signal, the "-" side isn't the same as the chassis ground in the truck.

If the whine changes pitch with the speed of the engine, then that's typical electrical noise, and it's coming through the power lines. It can easily show up in just one side of a system instead of both. This is the weird thing about inductive noises.

To get rid of it, you need to isolate the power lines from the chassis which is done through the use of an "isolation transformer". One of the links at that Crutchfield link above points to this page:

http://www.crutchfield.com/S-eHtPxZ9...p.asp?g=181150

From there, you can eliminate the antenna iso modules, so you're left with trying the line level iso's or the electrical. I would place dibs on the electrical side.

Given that this happens with the fuse pulled in the amp, I think that the noise is being injected at the head unit. That means you won't need a high current iso, so this one would do fine:

http://www.crutchfield.com/S-eHtPxZ9...1150&I=003S15A

This will install in the + side of your power wires feeding the head unit.

It should fix the problem... if it doesn't, then the 2nd step is to isolate the audio, which would require something like this:

http://www.crutchfield.com/S-eHtPxZ9...1150&I=127SNI1

That would install betweeen the head unit and the amp. It may give different results depending on if you install it closer to the head unit or the amp side of your audio feed.


Sad to say, there's no real science that can be applied before spending money on devices to figuring this out. You kinda' roll the dice and try the options that are available one at a time until you get rid of it.

Sometimes you can get lucky and fix the problem by rewiring the power feeds, or re-running the audio feeds. The next time you're in your truck, set things up so you can hear the noise, then reach under the dash and see if you can change how it sounds by juggling the power wires. If you can change the symptom, you can fix the problem. i.e., if you can change how the noise sounds by moving wires, then you've got a good chance of being able to get rid of it all together by re-running your power.

Toyrantula

I am going to start with the amp.

How is the amp mounted? The chassis of the amp SHOULDNOT be bolted to the body por any other metal. Glue a board in place and then screw the amp to the board.

To isolate the amplifier as causing the ground loop, get an old pair of RCA`s and cut them. Now wire the 2 inner wires together . Then plug the looped RCA`s into the input side of the amp. If the noise is still there it is a grounding issue.

Possible causes are chassis grounded to the body, A bad RCA cable that may be pinched, or bad grounding point of the negative wiring to the body. A good clean ground (scrape away paint, better to drill a hole and use a tooth waher and bolt) dont use a seat bracket bolt.

Check the grounding of the headunit.

What shape are your plugs and wires in? No shorts or low impedence on the wires?

colsoncj

Not to hijack the thread, but why should an amp not be bolted to the truck? Mines bolted to an aluminum bracket which is bolted to the body. PM me with info, as not to hijack the thread. thanks :-)

AgRunner06

Ok I've got some more info for ya. The noise only comes through that back driver's side speaker when I turn the parking lights on.

As for the amp, it's sitting on the carpet next to the sub and not screwed in. As I said before, there's no power running to it because I pulled the fuse on it.

The plugs are about 20K miles old and the wires about 30K miles. Both should be fine. However I'm going to change the plugs for other reasons.

Thanks for the input guys.

Toyrantula

Bolting an amplifier, line driver etc, to the body can cause a ground loop.

How is the stereo wired in? Did you cut the factory plugs off or use a harness adapter to wire the deck? How is your power being run for the amp? And lastly where are you getting the amplifiers remote lead turn on power from?

AgRunner06

Ok, if I remember correctly the deck is cut and wired in with wire nuts. My power wire for my amp runs through my firewall and under my carpet along the driver's side doors. My remote wire is run into my power antenna signal.

I've found that I can make the sound stop by reaching up under the dash and pulling on the wires that go to my deck. So I'm sure it's a bad connection there. I'm going to be ripping out my sub soon so I'll fix it then.