Buzzing noise when backup camera is on. 2008 Dynasty

[Doug and Nicki]

I have a 2008 Dynasty with the Kenwood KVT-M707 wide lcd monitor receiver (with backup camera) and the Kenwood LZ-702W wide LCD touch screen monitor. on a recent trip, i started getting a buzzing noise from under the dash. The noise is constant, even when the engine is not running, but increases with engine rpm, while on the road. The buzzing seems to be coming from a gray box on the inside firewall. The only way to stop the noise is to pull the radio fuse in the outside control center bay. Have any of you experienced this? If so, what did you do to correct it?  Does anyone have suggestions?

[DavidL]

Sounds like you are getting ignition or alternator noise in the cable.

Is yours a diesel pusher?  If so, then likely not ignition.

You might have a ground loop in the Kenwood installation.  Usually heard through the speakers...what is the gray box?

A choke installed on the kenwood power line might help.  But that's just a guess right now.

[MyronTruex]

Have you made any modifications lately?

[Doug and Nicki]

On 11/30/2022 at 6:48 PM, myrontruex said:

Have you made any modifications lately?

No modifications have been made.

On 11/30/2022 at 6:48 PM, myrontruex said:

Have you made any modifications lately?

No modifications have been made.

On 11/30/2022 at 5:20 PM, DavidL said:

Sounds like you are getting ignition or alternator noise in the cable.

Is yours a diesel pusher?  If so, then likely not ignition.

You might have a ground loop in the Kenwood installation.  Usually heard through the speakers...what is the gray box?

A choke installed on the kenwood power line might help.  But that's just a guess right now.

The gray box appears to be for the CB radio. I have disconnected the power to that, but the noise remains. PLease expand on "choke". Is this device something I can buy online?

[Tom Cherry]

My take….based on your comments are sort of “broad brush”.  I had a similar problem, and I can’t recall if it was on my Camelot or Winnebago..  First verify that there is not a mIcrophone on the camera.  Second,  is there a volume control on the monitor or receiver for when you could it as “monitor”.  I fed an AV signal into my Camelot monitor and used the AV AUX input from a smartphone and ran Google Maps through that.  So, please take this professionally, make sure that there have been no inadvertent or bumping or changes to the backup system and understand the controls and where a “RF” buzzing sound could be picked up.

OK…..I wrote a lot….and then kept digging.  Your radio is similar to mine.  I also looked at a lot of pages in your owners manual.  You have the “stock” system….so here goes.

Next.  The “gray” box needs to be identified.  Was it “buzzing” before or has it always buzzed.  YOU NEED TO POST A PICTURE.  I consulted with a 2008 Dynasty owner,  there are TWO potential Gray Boxes,  one is the “base” for the Cobra hand held (remote) CB radio.  That BOX may be on the same FUSE as the Radio,  you will have to look at the fuse layout,  if that box is for the COBRA and buzzing, then something is broken.  Many folks actually upgraded their CB’s and pulled out the entire gray box and used the power leads and antenna leads for a different CB.

I have NO idea what the box’s connections are….but it does have to have two power wires and an antenna.  If you did not cut or kill those lines and it is buzzing, since it is a radio….it could be your issue.   Need specifics,

If the .gray box is the Siris XM receiver, it too, is powered by the radio fuse…..but it plugs in and is easily removed.  
 

If you could post a picture, then other Dynasty owners might assist you.  Maybe you have or had the optional Factory CB.  Should be some sort of label or name on the gray box.  I had a Siris XM option connected directly into my Mgnadyne radio (2009….but used for many years prior).  It was Gray.  It had a small antenna wire (screw or push in, can’t remember).  There was a mating connector to the Magnadyne radio that fed in the XM signal.  If all you did was disconnect the antenna line and not chase the Magnadyne connector and it is “defective”, then that MAY/COULD be the source.  Follow the wires….antenna and input to the Magnadyne.  The Antenna can dangle…..but the Radio is feeding power to the XM Receiver box.  I killed my subscription and then removed the box.  Follow the cords and unplug the Gray box and totally remove it,  you do NOT have to cu any connections.  There should be an XM or SIRIS name and logo on the box.

EDIT. Until we have pictures or until you do some trouble shooting…..it is impossible to do much more. BUT, I had written some technical explanations and I will leave them in and not do wholesale editing…..
 

BUT, you also DO have a Volume up and DOWN on the Kenwood as it has a DVD player for the Navigation system. So…

Make sure the Volume, assuming you do use the GPS, if you have it, through the Kenwood.  If you use it….then turn down the volume and test it.  Did the noise go away?

Next, assuming the Gray box is the Siris and you don’t have a subscription….then follow my instructions and totall remove it.  IF for some reason the radio was accidentally set for XM/Siris and the box is defective…maybe the RF buzz.  Removing the box will shut it off….as it is NOT in use.  The power for it comes from the Radio…so killing the radio fuse is the ONLY way to shut it off.  The Radio was designed and will operate without the Siris box….I have done that for 13 years…do the above and report back….the rest is “information” about your choke…but even if you cut into the radio power lead and put one of these on…I doubt it will solve or fix I it

OR   Identify the leads for the Cobra Cb base and if it won’t stop buzzing, disconnect or cut the power leads.

Finally….a “Choke”.  That is a device to filter out leaking Radio Frequency noise.  Think about it this way.  Your shore water hose always delivers clean and NOT MUDDY water.  You have “lived” or been permanently parked at that site for years.  You do NOT have an in-house water filter.  Then one day, you get muddy and smelly water.  A charcoal filter element in a water filter will clean it up…..so, you add that.  BUT, you have NOT addressed the source.

Here is a Choke (as in it chokes off or removes noise on a DC power line).  It is the equivalent of adding a water filter….

https://powerwerx.com/dc-line-noise-filter-powerpole-connectors

BUT….the real question is WHY NOW.  If you check the backup camera system and monitor, then if nothing has changed…..you have to look elsewhere.  Add in a choke or filter is not solving the issue.  When folks install new equipment, sometimes there are ground loops and things make “noise”.  If you can’t revised the circuit or fix it….then adding a choke is the only alternative.  BUT, you didn’t make any changes.

Something is emitting a noisy RF signal.  On a Gas engine, you have a high voltage “pulse” that comes from the ignition module and then each pulse fires a spark plug.  The FASTER, you drive, the faster the frequency of the pulse….so a leaky ignition module or a bag coil or bad spark plug wire…..the louder it gets.  It actually doesn’t, typically, get louder.  The time between the pulse is reduced….so it sounds louder as it goes from sporadic to almost constantly 

 

[MyronTruex]

Could be a speaker connection have come partially apart.

Shoot a video and post so the sound can be listened to. The pictures will help of course.

Chasing those nasty things can be a lot of trial and error and some dumb luck. I have spent hundreds of hours chasing noise in radio systems and it is not easy even with top notch test equipment.

I just wanted to suggest something simple. Tom has gone to a great deal of thought and effort. 

If you can find where the speaker wires are and they appear to be tightly connected, try unplugging one at a time to see if it goes away. 

Edited December 10, 2022 by myrontruex

[Doug and Nicki]

Update. After contorting myself to see better under the dash and also cutting some wire ties to move the wire loom a bit, I see a small black speaker. I have not yet determined exactly what it is for. Possibly the air system siren while coming up to pressure. I have more work to do to try to unplug this or to remove it altogether to a place where I can evaluate things better. I will report back after doing some more research.

[pwhittle]

The rear cameras often have a microphone in them. Perhaps you are hearing that when in reverse.

Paul

[Doug and Nicki]

It was a speaker for who knows what. I snipped the wire and everything else seems to be working. The buzzing has stopped, so I am happy at this stage.

[Ivan K]

Maybe a CB speaker? I got one in the center console.

[Tom Cherry]

2 hours ago, Doug and Nicki said:

It was a speaker for who knows what. I snipped the wire and everything else seems to be working. The buzzing has stopped, so I am happy at this stage.

Odds are it was connected to the CB GRAY box….most folks pulled out the CB “BASE” or the box where the Cobra remote head was plugged in…

[MyronTruex]

Outstanding. Some sort of ground loop issue. Glad you chased it down. 

I'm curious, was the sound loud or just an annoying low level buzz?