Noise Through Aux Port When Charging

[Sooty]

Hi,

I have a horrible high pitched whine coming through my audio system when I am using my MP3 player or iPhone through the Aux port in the centre console.

It only happens if I have the device plugged into the power socket in the console so that it is charging.

There is no noise at all when no power is connected to the device.

This happens when the car is booted up to ready mode and in accessory mode.

Does anyone have any ideas what is causing this and how to cure it please?

Many thanks in advance.

Sooty

[Raistlin]

The noise you hear is related to the ignition, and is due an improperly constructed input cable.

It is not the fault of the MP3 player.

You need to properly shield and ground the cable.

This can be done with mesh braid placed over the cable, and then grounding the mesh braid.

To improve the cable appearance, you can cover it with black shrink tubing, and heating it with a hair dryer.

[Dutchguy]

Sounds to me it's the DCDC converter that is charging the 12V Battery that causes a ripple on the power socket.

Are you using an original charger for your MP3? Cheap replacements may not have such good ripple rejection.

Theorizing this further, it could also be an older Battery that could result in more ripple as the internal resistance increases.

Note: I'm only a newbie with (non-automotive specific) electronic experience ... so see it as only my pence worth...

I'm sure there will be others who could contribute to this from real life experience

[Sooty]

Thanks Raistlin.

I take it that you mean the audio cable that plugs into the Aux port.

I will look for a shielded audio cable.

Failing that do you think that a clip on suppressor would help? A bit like the old ones that you see on some printer leads.

[Sooty]

Sounds to me it's the DCDC converter that is charging the 12V battery that causes a ripple on the power socket.

Are you using an original charger for your MP3? Cheap replacements may not have such good ripple rejection.

Theorizing this further, it could also be an older battery that could result in more ripple as the internal resistance increases.

Note: I'm only a newbie with (non-automotive specific) electronic experience ... so see it as only my pence worth...

I'm sure there will be others who could contribute to this from real life experience

Cheers Dutchguy.

The Battery was replaced last April so I doubt that is the problem.

I am using a genuine Apple in car charger.

[cew]

This is due to the presence of electrical interference from the vehicle as others have suggested. I had exactly the same problem with my Mk2 Prius despite good quality cables (unsure if shielded or not).

To rid yourself of the problem you need a 'Ground Loop Isolator' eg - http://www.pyleaudio.com/sku/PLGI35T/35MM--18-Stereo-Audio-Ground-Loop-Isolator I can personally recommend that particular brand. Using this, the problem is now completely eliminated. It basically plugs in between your vehicle and the 3.5mm lead (no power required). For some reason very few shops seem to sell them, I found mine on eBay but needed to be imported from mainland Europe which took a couple of weeks.

I think Toyota do have a replacement 3.5mm port available which can be fitted to the vehicle with a ground loop isolator built in. However I'm sure it probably costs a lot more and is more expensive/difficult to replace if/when it breaks.

Hope this helps, if you've got any further questions please feel free to ask.

Sent from my iPhone using Toyota OC

[Sooty]

Cheers Chris.

I will look into this.

I'll also ask Mr T when the car goes for her 60000 mile service soon.

[cew]

No problem. Have just had another look around and seems that some have experienced a drop in audio quality with Ground Loop Isolators. (See http://streamingfreebies.com/blog/2012/04/fixing-the-prius-ground-loop-hum-without-sacrificing-audio-quality/) Can't say I have noticed but that blogger seems to suggest the clip on Ferrite cores are a better option?

If you Google 'Prius Ground Loop Isolator' there are lots of forum posts out there including info on a free repair service Toyota seemed to offer in the USA a few years ago.

HTH

Sent from my iPhone using Toyota OC

[Sooty]

Guys.

Thanks for your help and suggestions.

I have been out and spent a fortune. I spent £6 on two ferrite core clip on suppressors.

With just one clipped onto the audio cable there was no annoying whine when plugged into my iPhone whilst charging.

However I was getting some feedback from my MP3 player, so I put the second suppressor over the negative cable for the power socket extension from the console and ALL feedback noise has gone.

So for the princely sum of £6 I have sorted the problem.

Thanks again for your help.

Sooty

[Sooty]

I have spoken to Toyota, the main dealer in Stoke and they have told me that there is no Aux socket with built in Ground Loop suppression on their catalogue.

They even said that the best way was to put the graphite suppressor cores around the cables.

[johalareewi]

The usual way to fix a ground loop situation is to break the loop.