Weird AUX Problem

[gannet]

Hello,

Hoping for some guidance or suggestions....

Ever since fitting my AUX-IN socket shortly after buying the car It has been functioning correctly and without problem. For most of the time it has been hooked up to an iPod amplifier type thingy made by Belkin which provides iPod charging and a dock connector.

Since wiring up so that I can use my phone (HTC Desire HD) for phone calls without using bluetooth and also music and sat nav I have the following very strange problem...

All is fine for about 30-60 minutes, ie I can listen to music stored on the phone, make calls and hear sat nav directions all through the cars' speakers... after that amount of time however the radio in the car decides to switch the input to the radio. I can switch it back to AUX again, but that only lasts for about another minute or so before switching back to radio

Any ideas what could be causing this? :?

Thanks in advance...

 

[Greeno]

There is a known issue with HTC desires, both the standard and the HD when using 3rd party headphone jacks.

is it always after an hour?

Tracks skip as the phone gets confused periodically as the 3rd party jacks dont fit perfectly.

the phone then thinks there is a headset plugged in and and periodically thinks it is getting signals from the control on the headphone cable to skip the tracks. could it be related??

Look on the phone when the aux switches off, is it showing the head phone symbol or is the headset?

this can be resolved by running the headset blocker app.

perhaps if it is swapping over to the headset setting then it is somehow confusing the head unit. it might be that it happens after a while as you might be getting a good connection initially then a bit of driving jiggles the jack.

Drove me insane the track skipping till i found the app

 

[gannet]

thanks for that

To be honest I havent noticed the icon changing from the headphone icon, but you never know. Good to know there are others with something odd..

No harm in trying the app - I have downloaded the app and installed... will report back.

Any other ideas?

 

[nfc]

I also have this problem, but with an iphone running through a tomtom cradle - I think the iphone overheats with this combo and it's the phone with the problem, not the aux input, as I can run other devices to the aux input for hours without a problem..

Cheers,

Nelson..

 

[playalistic]

A longshot, but do you have the traffic reports thingy turned on on the radio? The thing that you can enable that cuts in regardless of which source you're playing and gives you the traffic updates from local radio...

 

[gannet]

Thanks for the replies so far...

it is not related to traffic reports and the headset blocker app didnt help...

what I have since noticed is that it related in some way to whether I have the phone charger connected to it or not :? Using a USB lead taking it's charge from a Cigarette lighter expansion socket with a USB socket integrated into it...

Guess I will have to check the voltage/ampage of that source?

any other ideas people?

 

[J4YMO]

I have the same problem with Iphone - plug it into the charger and aux disappears!

See this link here for someones explanation - hope it helps:

http://www.z4-forum.com/forum/viewtopic.php?f=2&t=20588&p=299533#p299533

 

[gannet]

aha, so there is an explanation.

might be worth getting one of the ground loop isolaters....

such as this one?

 

[J4YMO]

I have no idea - not the most technical! But if you try and it works please let us know.

Presently I just try make sure phone charged in advance of journeys - easy way out - if annoying!

 

[gannet]

I PM'd yg54sg to ask he had done the suggestion and he pointed me towards a bluetooth headset solution....

bit more expensive though...

 

[gannet]

just thought I would update...

I bought a ground loop isolator and problem solved

 

[jamjia]

What was the cause after all??? I'm experiencing exactly the same thing and I have a iPhone 5...

 

[jamjia]

This is such a stupid problem. Is there a proper fix for this?

 

[bcworkz]

Hi jamjia, in gannet's case the problem was when the phone is plugged into the charger, a second ground path was created that had a different resistance than that through the head unit. The difference in resistance causes additional current to flow through the AUX cable. The head unit detects this extra current and switches to another source to protect itself. This induced current is called a ground loop, thus a ground loop isolator blocks this current, keeping the head unit happy. A ground loop isolator is basically a transformer so that there is no physical connection between the ground paths.

If this is what is causing your issue as well, the only possible solutions is either to not charge while using the AUX cable or to isolate the phone ground from the head unit ground with a ground loop isolator.

 

[jamjia]

Thank you for the reply and careful explanation. I really appreciate it!

I do sometimes charge the phone and so have purchased a ground loop isolator.

I just found it odd that such an issue would not have been discovered by BMW during QA testing and a fix then issued.

 

[bcworkz]

As reluctant I am to defend BMW, this issue does not happen to everyone. It depends on which devices are connected. They can't possibly test all combinations, and certainly not equipment that has not even been manufactured at the time.

But I'm inclined to agree with you. They tend to have an attitude that they are not responsible to ensure compatibility with anything not officially BMW and write it off as a fault with the charger. They also probably were more focused on phone cradle compatibility with the most popular devices of the time and did little testing of cigar lighter charging devices. The AUX cable was certainly not high on their important features list, I wouldn't be too surprised if they never even tested the AUX cable connected to a device whilst charging.