hefu

Hi there! This is my first post, although I have been lurking around for a long time.

I have a 2004 Cayenne Turbo, with the Bose system.
I had a small encounter with a fence on the highway earlier this year, and when the car came back from the shop, the stereo isn't working as it should.

From time to time, at no regular interval, the stereo stops sounding, except for the bass frequencies! Drive for a while, and it comes back! VERY annoying.

My service guy at the Porsche service center had no idea, but claimed it wasn't since the accident. "It is a very complicated car..."


I'm thinking something isn't connected as it should, or is there a crossover or something that is about to break down?

Thankful for any help.

ltc

Describe "bass frequencies"

Is it the actual music/voice but just the lower frequencies or is it just low frequency rumble/noise?

Is it from all speakers?

Does it respond to balance/fader control?

Are you allergic to penicillin?
What is the current tire pressure in the front left tire?

Does the headunit respond to changing sources or channels when in this condition and does the low frequency noise follow the source?

Where was the car hit/damaged?

hefu

Bass Frequencies, in other words, just the lower frequencies of the music.
Lot's of bass.
From all speakers. Adjusting the fader or balance does not affect anything.
Doesn't matter what source, CD, radio or iPod.

The car was hit on the driver side, or rather graced. But, in about 65mph or so some damaged occur.

Not allergic to penicillin, but I do have size 12 shoes, extra wide.
Plays the drums for a living.

Renn 951

It's not the car; you are just beginning to lose your hearing!

ltc

iPod?
Not a standard peripheral on the 2004 P!g ... what are failing to mention?
Is there an aftermarket peripheral? FM modulator? mOBridge, NAVTV, Dension?

Interesting that it is coming from all the speakers and not from just the powered subwoofer in the rear cargo area. You're sure it is all the speakers and not just the subwoofer? low frequency is hard to locate and discriminate ... design defect in humans.

I also assume there are no error messages or "!" being displayed in the vehicle and that the battery has already been checked.
If the MOST ring were intermittent, you would have no audio (by design) and likely display an error message about "Can't find xxx component".

The most logical guess would be the amplifier (rear cargo compartment, passenger side, underneath the trim panel, not too far away from the dreaded 1D6 factory towbar control unit ...no, do not go there), but I am frankly at a loss to describe how the amplifier's equalization (which is all DSP based) could fail in such a manner. I don't recall ever seeing such a failure.

Larry would probably know, but he's dead and I'm not planning a trip to the cemetery anytime soon. Besides, he hated even numbers, so having a size 12 shoe would definitely disqualify you from getting his opinion.

hefu

You are of course right. Size 12 is a burden.

The previous owner installed an iPod dock, I think Dension.
I am sure that the sound is from all the speakers. No error messages on the displays, actually when I had the car at the bodyshop, they didn't get any error messages with their stuff!

ltc

When the stereo stops working and produces just bass outputs, does it still respond to volume control or is it a fixed output level?

I would not expect this problem to produce error codes.

Have you verified that in fact the entire OEM audio system is still in tact? Anything else besides the iPod dock?

Also, is this a PCM or CDR-23?

When it starts working again, is it after a key cycle or whie still driving?

hefu

It does respond to the volume ****.
Nothing else besides the iPod Dock, everything else is original.

How do I check if it's PCM or CDR-23?

When it starts working again is totally random, it can't be connected to the ignition.

ltc

How many interior panels were removed during the repair process?

I am unable to come up with a fault in the Amplifier schematic that would cause such a shift in EQ, based on your description.

The most likely place to start would be shorts (or perhaps opens) in the amplifier output wiring harness / connector.
The mapping between the available amplifier output channels and the total number of transducers would support such a scenario...but it's the first time I've heard of it occurring.

This can not be located via S/W diagnostic tools or codes. It must be done the old fashioned way...visually inspecting and moving speaker wires to try and replicate the fault.
Wiring harness issues regarding intermittents are the worse. I have seen P!gs completely gutted inside during this process trying to locate the fault.
Even when the fault is located/verified, the harnesses are VIN specific, made to order and long lead time items.

In your case, once located, it can easilly be repaired.

BTW, the CDR23 is the half DIN height headunit, the PCM is the double DIN headunit with the color LCD display.

hefu

Ok, I have the PCM with the Navigation.

I remember a thing they said when I picked the car up at the body shop...
They had no sound in the stereo, and had to take stuff out again.
Finally the fault was a fuse underneath the battery under the driver chair.

Anyone have any pictures of the amplifier and its connectors?
My brother in-law used to compete in car stereos, and know his way around wiring, maybe we should give it a try...

ltc

The amplifier has 3 connectors. It is actually same same amplifier used in Porsche, Audi and Mercedes (and the Maybach). The amplifier's code name was Autobahn...

Loos like this, all connectors on one side

http://www.ascendtech.us/porsche-cay...7l5035456.aspx

1. MOST optical connector....orange fiber in, orange fiber out.

2. Main connector....12VDC unswitched, speaker outputs. It is a cam type connector

3. Interface connector...again a cam type, smaller, misc signals.

It is mounted above the CDChanger, rear cargo compartment.
http://www.panix.com/clay/cayenne/sound.html


Nota good sign when the fuse under the driver seat goes....something very bad happened.

EnigmaWmn

This is totally OT, but I'm just here to say:

I missed you Larry!

That's it

ltc

Not back. Just trying to help a newbie to the P!g Pen.
Besides, I view it as either:

A. Trying to pay penance for everything that Larry did while he was alive

B. just doing some advance work in preparation for Larry's return on 22 Dec 2012

hefu

I'm really thankful for the help!

What happened was that the airbag in the driver chair and the side airbag went off when I crashed, and the shop said that's why the fuse went off. I dunno....

Thanks!

seankrider

+1,111