Radio Buzzing / Interference / Noise

[6600DURAMAX]

I finally got around to turning the radio on the other day and now it makes and awful buzzing noise when the truck is running. Doesn't matter if I play a cd or listen to the radio. It does NOT do it when the truck is turned off and the key in the acc. position.

My first thought was the new plug wires I bought did not have the RF shielding, but upon further investigation the box they came in states they are RF shielded.

What now?

[72BlckButy]

Do you have an RF blocker installed on the radio? I remember having this problem with a vehicle and after installing an RF blocker the noise went away.

Aftermarket radio or stock?

[rwolf9653]

Sounds like you are getting feedback from the alternator.
Does it get higher pitched when you accelerate? Check or change your grounds on the radio and engine to see if it gets better.

[Devil Pup]

you mentioned cd player, are you running an after market head unit and possibly an amp to speakers or a sub? If so just change the remote wire to the opposite side of the cab that the power wire is running. it will stop it for sure.

[6600DURAMAX]

I did change alternators but all I did was get rid of the old one because it was only a 60 amp and replaced it with an identical 100 amp.

What is a RF blocker and where does it install, the radio never had one before??

It is an aftermarket Alpine head unit

thanks guys

[6600DURAMAX]

Yes Devil, I am running a sub with a remote wire, but I do not follow what you mean by run it to the opposite side of the cab????

[Devil Pup]

ok, basically when you ran the amp. . most likely its under the seat? you had to run a power wire to it from the battery and the remote wire to it from the deck. usually if you put the remote and the power down the same side of the cab "driver side or pass side" it will pick up interference and that's what your hearing.

[Longhorn Man]

it's more likely to be a bad, or more acuratly a 'dirty' ground.
moved to audio

[Devil Pup]

Ya i would say check the ground first regardless, thats the simplest fix. but i am pretty sure its the wiring

[AceX]

Ground loop noise most likely. x2 check the ground and add a second to make sure. You can also add a noise supressor to the wiring for the radio.

Some alternators are very noisy. If you can, try and find one made by Powermaster. They don't cost a ton and don't put out a whole lot of noise either.

[unclewatts]

Sounds like RF noise to me, not a bad ground. (although a bad ground can cause this) As mentioned earlier you need an in line filter installed between your power source and your head end. The filter is a Capacitor-based device that will pass DC but filter out RF AC. Cost about 6 bucks at most auto parts stores and I think even "Radio Crap" carries them.

[colgad]

Fixed my radio buzzing with replacing the capacitor in my brand new HEI Distributor. The capacitor is the square red block, some HEI's have the can style. Never the less the noise is GONE!!!!