ThomasJ

I have a very annoying whine coming through my speakers. It follows the engine RPM perfectly. The more load I put on the electrical system the louder it gets. Like when I roll up the windows it will get louder, or when I turn on the head lights. It seems it has been getting worse since it is cold outside. After about a half hour or more of driving the noise will stop.

I have cleaned the battery terminals and made sure they are good and tight. I cleaned the connections on the wire from the positive terminal to the main fuse box under the hood. It did not improve after any of this. I have no other electical related problems. It fires right up even in below zero temps, volt guage reads rock steady but drops slightly at idle with the headlights on and heater blowing.

I was wondering if anybody has had this problem before and what you had to do to correct it.

Also if anybody knows where all the main grounds are at that would really help. Im going to try and search for them and check them out tomorrow, but its been so dam cold outside it really sucks trying to work on somthing. If I know where to look it will go much faster.

Thanks

Sequoia'd

Either a diode is going out on the alt. or capacitor is failing in the audio system's power supply. Have you recently changed anything like plugs, wires, etc.?

midiwall

Head to Rat Shack and pick up a "noise suppressor" kit. It'll consist of a non-polarized capacitor and an isolation transformer.

What you're hearing is alternator whine. The frontend of the amp in your tunes is reacting to dirty power and passing it through to your speakers. It's pretty common, but (liek Sequoia'd implied) it's usually "caught" and remedied by stock components.

tc

While it could be the items mentioned above, it is likely a ground loop situation.

Basically, a ground somewhere is loose or missing, so that component has a different electrical base plane to work from. Do you have just the stock/aftermarket radio, or do have separate amps?

there is a post talking about improving the grounds on the 3.0, and it lists all of them in there. I believe there are three - battery to frame, block to frame and plenum to frame - but not exactly sure. If the weather ever gets above freezing here, I am going to look into mine because it is awfully slow to start up in the morning...

ThomasJ

Yes, I just put a new cap, rotor and wires on about two months ago.

The stereo is all stock. Factory amp.

i_rifiyou

your speaker wireing is not thick enough....i've had a few cars with systems.....your either changed the speakers or head unit, when doing so you need to thicken up the speaker wire only...simple fix

ThomasJ

Stereo is all stock. It makes the noise with it off or on.

DudeBud

ground problem. add or check grounds

tc

Ummmm - no. This is absolute garbage.


But - new plug wires? Did you get RF suppression versions? (What brand/model) The ignition system generates HUGE voltages that can easily induce an electric signal in any nearby wire. If you still have the old ones, switch them back and see if the noise goes away.

While I think it may work, I tend to stay away from the noise suppression doodads - it's just a bandaid, not a root cause solution.

Sequoia'd

+1 on what tc said. Possibly non-resistor plugs instead of the resistor type. Since you didn't have it before you changed out plugs, wires, etc. something must be up with the new parts installed. Additional grounds don't hurt but I believe it's something as stated above. BTW, RF interference can migrate through the speakers even if the radio is off... due to the way 12v systems operate. Considering that the '91 has several switched ground circuits, completely possible it's generated in one place and ends up coming out someplace else!

bleakhorizon

I got the same problem with my truck, but mine doesnt go away after 30 min or so like yours does, i tracked it down to the ground on my aftermarket amplifier had corroded in the terminal end..... My freind had a 95 that would do that and then "fix" itself ..lol so he put and aftermarket radio in it and that fixed it.... may be that older electronics is finally giving up the ghost, you may try checking the grounds for the amp/stereo also, maybe just give em a loosen then tightening....

RobD

I used to have a whining sound from the passenger side.

Then I got rid of my wife.

Bada bing.

1990yota-pickup

alot of the windining is coming straight from the alternator...

if you got boom boom speakers and amp that are pulling more then what your alternator is rated for you will get the winding no matter what you do... check all grounds first if that doesnt fix the problem put a higher rated alternator in the truck.. if you ge a 1 fharad capictor it will keep all so stop the winding.. cus it well not be drawing off the battery constanly..

93runner223

clearly car audio is picking up electrical interference mine does it to with my two amps even though my wires are ran on either sides of the car so if u have an amp unplug power to such and see if it still makes noise mine didnt so viola or whatever that word is

Magnusian

If it's coming from the alt, then it's AC line noise on the DC supply, that's very easy to take care of, you basically put a capacitor (non-electrolytic) between the noisy DC line (such as the power going into the radio) and ground. This causes all the noise to flow through the cap and into ground (i.e. between the red wire and the black one, though you'll want to make sure you have DC Power + with a cap between to DC Power -) and leaves you with cleaner DC and is known as "decoupling". We use this method all the time in the chip-design industry on the DC supply grid to keep signals clean and snappy and reduce overall line noise. You do -not- want to put a cap between the two wires going to the speaker, it won't kill the speaker, but unless it's digitally driven (and likely isn't, but if it is, this is actually a good idea) you'll end up filtering all the sound straight into the ground and get nothing side from machine beeps and stuff through the speakers and possibly fry the head unit. One of the likely causes for the OP's issue is that the decoupling cap inside the head unit or amp is toast, probably because the rectifier in the alt is too, and putting in replacement ones on the supplies should take care of the extra line noise from the alt, but it won't fix what's wrong with the alt. It's a good thing for any DC supply in to have a decoupling cap between DC power and DC ground and will reduce things from headlamp flicker (with headlamps that are DC-powered) to whining noises on speakers as well as extend the life of said components.

ET

HAHAHAHAHAHAHAHA! I read this in class and started cracking up. got a lot of weird looks from people...

Spence1016

get one of these

http://www.crutchfield.com/g_181150/...s.html?tp=3723

Richjrosa

I second this idea..

I know when I used to install aftermarket systems we would always run a return ground and ground everything at one point to avoid this exact issue. Really cheap audio equipment is usually the cause all that great rockwood and kenford stuff.

Squiddy

This just started being an issue for me after fiddling with the throttle body and various wires up there, can't find the source (its a crackle rather than whine, but same idea)

Magnusian

Check your grounds and all your power connections, it sounds like something is loose which would "crackle" as a result of vibrations. It's either an intermittent short or open, and I could tell you more if you give me some more details on the sound and when it happens (is the music continuous despite the crackle or does it "turn off" when the crackle happens). Make sure the connections are clean and solid and then check any wires you've recently fiddled with and make sure the insulation is intact.