Mobridge / PCM system noise issue - this one's a tough challenge&#

[prglewis]

I have a 2005 Cayenne S with a PCM 2.1. I recently had a mobridge iPod and Bluetooth unit installed into the car and I'm having an issue with some kind of system noise when listening to the iPod. The audio shop that did the installation and mobridge themselves haven't been able to fix it, so I'm wondering whether someone else knows of this and can help. Here's the full details on the problem:

- Hiss with a regular ticking noise at approx 1 second intervals.

- The hissing is amplified more in between tracks, in very quiet parts of tracks or all the time when playing audio books (basically when there's little other data / audio to amplify). So basically as a song ends, the hiss/clicking will fade up for a few seconds and then fade out again as the other song comes in. Or its there all the time when listening to audio books, its pretty annoying.

- A rep from mobridge was in town and they actually had a look at my car. They said that some of the components on the fiber optic loop might be running at slightly different clock speeds or slightly out of sync, which is causing the "system noise" which the mobridge unit is amplifying. Not convinced on this clock speed / sync reasoning personally, seems a bit like they're making excuses to not put any more time/effort into the problem.

- The mobridge guy tried replacing the unit, and the ipod cable, both didn't help. We also downgraded and upgraded the firmware and software with no luck on each version.

- I noticed a slight change in the type and pattern of the noise after the re-install, suggesting that the placement or positioning/bunching of the cables might have something to do with it...?

- My PCM unit is version 1. They suggested to update it (latest compatible version is 3.0 I'm told) but I spoke to Porsche and they think it likely won't make any difference. I'm hesitant to spend the $300 and not have it work.

Any ideas?

Thanks in advance.

Best,

Paul

[hahnmgh63]

It wouldn't hurt to update the software but I agree in that it is probably not the problem. I'll have the update discs back to me (lended them out) in a couple of weeks if you want to borrow them to do the update. This would be just the updating discs and you would still need a Nav Map disc.

[wvicary]

Have you tried a different ipod?

[xsrfs]

def try another ipod

[mudman2]

Ticking is usually power supply related, i would be looking at the ground and the circuit where the power is tapped into

[prglewis]

wvicary & xsrfs - I've tried with my iPhone and unfortunately the noise persists, and I think (but can't fully remember) that the auto shop guy tried with his iPod and it still happened.

mudman2 - The power supply seems like a good call, I'll speak to the shop about that one. What should I be looking for to see if there's a problem, or how would I check it? I'm a little annoyed that neither the auto shop nor mobridge bothered to check this out!

hahnmgh63 - that would be great, thanks. I'll send you a PM.

[hahnmgh63]

Does the interference seem to be greater or the same with the engine running compared to being shut off?

[prglewis]

No, same interference with the car on and off, I tested it yesterday evening and this morning.

Edited July 27, 2011 by prglewis

[djben]

I am having the exact same issue.

07 997TT. Installed it myself - it was pretty darn easy.

Got a thread going on 6speed about it, I won't link it because I do not know the forum rules here. Someone with a BMW had the same problem as well posted to bimmerpost.

Hmm. My first post on renntech? :)

I am thinking I want to find a new power tap and the issue is related to the tap going to the PCM unit, but I'm not enough of an electrician to go hunting around for the right wire.

Edited August 3, 2011 by djben

[mudman2]

The none speed related click implies an electronic circuit or can even mean alternator sometimes. I would go to a spare slot on the drivers side fuse box and try it temporarily to see is that works. By doing that your isolating other active circuits on the car. I think 42 is free. Remember there are 2 required one always hot and one switched

Welcome djben

[prglewis]

djben - thanks for jumping in, I looked up your other post on 6speed, interesting!

I had mine installed at an auto shop so I'm going to take it there and try the following:

1) Run the unit from the side fuse box

2) Run the unit from the PCM power supply with a power supply filter attached (I'm told its a $25 part approx)

3) Run the unit from the side fuse box with a filter

I'm also down to try turning off the CD changer. At the moment I get the error message (CD changer not found) every time I start the car which is annoying so I'd definitely like to get rid of it. However, the auto shop told me that if I turn it off then it can't be turned back on (ever). Seems weird, is this right??

I won't be able to take it back into the shop until late August, but I'll definitely keep you guys up to date on what happens.

I'll post on 6speed as well, I'm curious to hear Cartronics' thoughts.

[djben]

djben - thanks for jumping in, I looked up your other post on 6speed, interesting!

I had mine installed at an auto shop so I'm going to take it there and try the following:

1) Run the unit from the side fuse box

2) Run the unit from the PCM power supply with a power supply filter attached (I'm told its a $25 part approx)

3) Run the unit from the side fuse box with a filter

I'm also down to try turning off the CD changer. At the moment I get the error message (CD changer not found) every time I start the car which is annoying so I'd definitely like to get rid of it. However, the auto shop told me that if I turn it off then it can't be turned back on (ever). Seems weird, is this right??

I won't be able to take it back into the shop until late August, but I'll definitely keep you guys up to date on what happens.

I'll post on 6speed as well, I'm curious to hear Cartronics' thoughts.

Any updates? I got my mobridge swapped out just to try something and it didn't help.

[gs3_4me]

Bringing this post back up to the top...

My recently self-installed unit is doing the same thing... the Hissing isn't always there, but does show up at times between tracks or when the sound from a track is very low.

Did anyone find a solution to this issue? Was going to call Mobridge/Cartronics next but figured I would check on here first... TIA.

[mudman2]

The unit should be silent. I just installed another on my 08 and its perfect. I would stick with tracking down the power feed. If you use the same feed as the PCM it should be silent. See the youtube videos.

[gs3_4me]

Hi Mudman. Thanks for the response. I might have to recheck the install, but am pretty sure that I tapped the power lead from the line running into the PCM and not another source, and kept going back and forth from my car to my laptop to rewatch the video. Is there more than one power line back there behind the PCM?

Also, I tried another ipod tonight and hear the same noise, unfortunately.... but only hear it when the volume is low on the track and between tracks... not when the majority of the music is playing though... I would have thought it would do it the entire time if it was a power supply-related item, right? (sorry, I definitely not an engineer or electrician, so no idea if that assumption is correct or off-base). :)

Edited February 23, 2012 by gs3_4me

[mudman2]

OK well the next thing to look at is antenna affects, where did you run the ipod cable ? ,maybe its running around a power cable somewhere

[gs3_4me]

Good point... will take a look at it this weekend and see about some alternative routes... currently, it is in the footwell/by the firewall, with the cable running along the side of the console until the handles, and then just routes to my passenger seat.

Thanks much!

OK well the next thing to look at is antenna affects, where did you run the ipod cable ? ,maybe its running around a power cable somewhere