JARO

THis jut popped-up today...no sound, PCM display shows everything fine but every time it is turned on it dispays above message. Did you guys have that issue? What went wrong and how was it fixed?

mudman2

I have not seen that but it does sound like a BUS error, dealer (unfortunately)

MadFox

Yup. I had 3 PCM's.. I think this was the message one time but hell who can remember now?! I know a few times it was just a dead screen and no sound or functionality... Early PCM's had lots of software glitches and they usually just popped it out and replace it.. they may be able to re-load software now.. LET US KNOW... SO SORRY... need a pencil or straight jacket?

JARO

PCM is fine, displays and all...Single CD changer fine as well but no sound at all....and the CD changer not working....PCM was repalced some few months ago...

356driver

I think there are still some ghosts in the MOST Bus that connects the PCM to the amplifier and CD changer. The MOST Bus is somewhat like a computer network but in this case the "computers" are your PCM, the CD changer and the amplifier. The MOST Bus operates on the principal of these "computers" communicating with one another. When you start the system, the PCM audio unit, amplifier, and CD changer identify themselves on the network. That's where things can go wrong, because if one of them fails to identify itself or if there is a communications error with a one of them, it is no longer "there" on the network.

The most typical way to fix this problem is to "reboot" the system. Yes, just like you do after the "blue screen of death" appears on your desktop system, this network of "computers" can be rebooted. It is important to understand that your Porsche keeps the PCM in standby mode most of the time, even when the ignition is off, so the system rarely reboots itself. So you have to force it to reboot.

I am going from memory but I think the way to force a reboot is to insert your key in the ignition, turn it to the on position without stepping on the brake pedal, wait 10+ seconds, and turn the key off. After that if you start the car and the initial "Porsche logo" screen appears on your PCM, then the PCM is rebooting. The audio head unit, the amplifier and the CD changer will re-register on the network and you should have sound again. Most of the time this will fix the problem but not always.

(Someone please correct me if I got the reboot procedure wrong)

If your system still fails to recognize the amp and CD changer you need to take it to the dealer. There were software upgrades to the PCM more than a year ago and you should have them by now if your dealer was keeping up with the warranty campaigns. Other possibilities are failure of the networking logic in any of the three units (PCM, CD changer or amp) or that the fibre cable itself has become broken or disconnected.

Lewis, anything to add?

ltc

Well, I should defer this question to the "masters of MOST".....www.densionusa.com.
But since they appear to be busy preparing their MOST aux interface for release ANY DAY NOW and are too busy to come to the phone, I guess I could act like I know something about MOST (after all, I did stay at a Holiday Inn Express the other night.....hiding from the bloodhounds after my "escape" from the "vacation villa" on a fake day pass.

Ghosts? That would suggest it's dead. No, the bugs in the MOST system are alive and well, thank you very much. IF you think this is bad, just wait for the 2008/2009 infotainment architecture.....DTCP over MOST!

Question:
Is your audio/infotainment system able to play audio from the other sources (CDS, AM/FM) when the CDChanger is 'broken'?
If so, then your MOST physical layer (plastic fiber optics) are in tact, as MOST is a 'ring' topology (headunit to amplifier to CDChanger back to headunit)....break the ring at any location and the system should time out and shut down.
Question:
Have you ever had your infotainment S/W updated via PCM replacement and/or repgrogramming? The devices on the ring can be S/W updated via an update CDROM placed into the headunit's CDS slot. There have been numerous software updates for all the components...your dealer can do this for you under warranty.
Question:
Did you install the CDChanger or was it a factory installed option?
Question:
When the CDC is 'off line', can you hear the mechanism inside attempting to initialize (i.e.: trying to determine how many discs are loaded in the cassette?). If so, this will verify that you do have in fact have 12VDC present; the absense of which would obviously cause the CDC to be reported as being 'off the ring'.
Question:
Are you allergic to shellfish....sorry, just love that line from M.I.B.

Best of luck,

JARO

well, sounds worked when I went out for lunch...just turned the car on and it was all back. PCM has the latest version of software and it is OEM CD CHanger. Display works, I can even see that the singel CD is playing and able to swith csongs and station but sounds was not coming out....Will try the reboot if it happens again. Thank you all for the suggestions and I admire your knowledge of this stuff.

pingwrx

I too get this message every once in a while. I would have to stop and restart the car and every time it comes back fine, but kind of a hassle to pull over and restart.

I was just a the dealer for my 20K service and mentioned this problem to them. And when I picked up my car, they said that they couldn't find anything wrong, but they reset the software...whatever this means. Anyway, as I drove away from the dealer I hit the stereo on button and guess what popped up on my screen: System Error: Amplifier. CD CHanger not avaliable. So I have another appointment at the dealer next week...we'll se if they can solve this problem.

ltc

System Error: Amplifier?!

We ought to find out who designed that !)@($*%&!@ amplifer and......oh, I don't know.....lock him up in a "vacation villa"

On a SLIGHTLY more serious note, the most likely causes (assuming they did in fact load the latest S/W updates for the MOST infotainment devices) would be:

defective amplifier assembly
defective plastic fiber optic cable/termination from headunit to amplifier.

Please ask the dealer to 'wiggle' the MOST connectors (and as much exposed plastic fiber optic cable) as possible at the back of the headunit and at the amplifier/CDChanger (rear cargo compartment, passenger side, behind removable panel) while the system is running and see what happens (loss of audio, system errors displayed, etc)

techm8n

I received the same error once (System Error: Amplifier. CD CHanger not avaliable). I had to turn off the car and pull the key out of the ignition. When I restarted it, the error dissappeared.

I also received a PSM error and ABS error once and following the steps above resolved the issues. I hope these electronic gremlins don't come back. For know I still like my Cayenne.

Did anyone else encounter some kind of electrical issues?

JARO

went to dealer and it turns out it had to do with the order in which the software detects the different components. Looks like it is all ok after they reconfigured it.

pingwrx

Jaro,

Can you explain how your dealer reconfigured it? I have an appointment this week with my dealer and I would like to show this thread to the dealer. Thanks.

JARO

no idea how...they ust re-configured the order in which the devices are being initialized or detected on the MOST network...

ltc

Trust me, you don't want to know. Just remember, S/W fixes everything.

JFScheck

Hey LTC...

Just curious, why the heck did the "MOST Brain Trust" go with a "Ring" topology verses "Star"?