hexagone

NwGTS and I had met up to clear an airbag light and some other warnings in Durametric, and when I pulled away all I could hear is the bass from the back, but no sound. Radio/iPod, all of them the same.

Restarted the car, cycled the radio on/off, locked doors, waited - no change.

Next up maybe - fuse? We didn't touch anything in Durametric to affect radio - but thought that was worth mentioning.

Posting here because I'm about to go on a 3000mi road trip and it may be nice to have the sound back

Bruce In Philly

2009 C2S 132K miles

Yep, you PCM is failing. Mine has been doing this for two years. I believe, I don;t know, that it is related to thermal shutdown. If you shut the whole system down, including maps, wait 20 mnts, it fires back up. I also noticed that if you play loudly, it happens sooner than softly. The trick is don;t shut the unit down. If it is hot, and you shut it down... say to get gas.... it won't fire back up.

f it is really failing, you have a bunch of years still in it as mine is behaving this way for a while. Could it be a little fan failed and not cooling? Is it in the amp/processor under the passenger seat or in the PCM head unit itself? Total conjecture: I bet it is a fan that failed in the PCM head unit. I could swear I would hear a fan in there sometimes but no longer.... hmmm.... I don;t really know.

Peace
Bruce in Philly

hexagone

Bruce In Philly

It is nothing you did... this is common... others will chime in here with the same issue. The amp/processor is under the passenger seat bolted to the chasis.. it is grey and the size of a paper back book... you will see it. That amp may not be the issue.

Peace
Bruce in Philly

mikes70

Mine failed in summer of '16, car being an '11 C2S. From what i can tell, and its pretty tight lipped, i think it may be a software issue with XM being a common denominator. I've lost three (one being the PCM) receivers with XM in the last 6 years. I'm a huge XM fan, so i just replace them. Panasonic made the Porsche PCM from what i was told, and made a large percent of the OEM's, My good friends' Lexus, same thing.

Petza914

If you're getting bass from the rear subwoofers, the PCM is working correctly and outputting a signal. What isn't is the Bose amp that drives everything except the rear subs. The rear take the raw signal from the PCM and it has its own small amp built into the sub enclosure. All of the other speakers are driven from the primary amp, which in a coupe I think is in the frunk and in a cab along the floor near the center console on the passenger side, but maybe the locations in a 2 are different. The Bose amp should be fused so that's the first thing to check.

Bruce In Philly

Most likely true, however I doubt the sub is taking the "RAW" signal. The PCM system is a 5.1 format that actually plays 5.1 DVDA discs. I suspect, but don't really know, that the amp/processor under the seat is translating the incoming signal and sending the .1 to the sub... it all depends where the real processing is done. Regular stereo, such as from radio has to be processed to send appropriate signals to all the speakers including the .1 sub. Again, I suspect the amp/processor is doing a bunch of work and the sub's electronics are just a simple, cheap digital to analog converter and not a decoder chip to decode the .1 sub information or create a sub signal for the bass as is needed from a stereo FM signal. But I really don't know. It would be a cheaper system to do all the work, one time at the amp/processor since the premium 5.1 system is an option. But true, all my conjecture. If I had to bet, I would bet the amp/processor's output transistors are overheating and the system is shutting down there. But who knows?

The only thing I am confident about is that the problem is thermal-related shut down and this is based on my ... oh two years? ... of experience with this problem. Of course, the question is why is it over heating, assuming I am correct? Does the amp have a little fan in there that failed.... this would be a cheap easy fix, or are the electronics just wearing out?

Update: the part number is 99764544101 ... I examined, the best I could... the pics of used units for sale around the 'net and it doesn't look like there are fan vents... heat sink fins for sure, but no fan vents. Oh well, I guess replacement is the only option... looks like $300 to $350 used. I look into this every so often and come to the same conclusion: wait till it stops working.

Update2: I just sent Becker in NJ an email asking for help... I will post back what they say.

Peace
Bruce in Philly

Petza914

Attached is my Focal speaker upgrade DIY on my. 1. It includes useful info and pictures on the rear sub connections, wires, and internals.

vern1

Mine just failed, its the 2.1. It started doing weird things like switching channels on its own or changing sources. Then it would just stop working at times and start up all of a sudden; not work for days then again start up when driving. I thought it was a problem with the hardware.

Anyways replaced with a new HU with a MOST bridge but not satisfied with the sound. Problem is that if you retain the bose amp you can only get 2 channel sound. Petzas route is prob best best more time consuming and expensive.

larrysb

Yeah, it's probably the amp under the seat. I'd say it is worth the effort to re-seat all the connectors on the amp unit. Could be something easy.

The head unit sends encoded audio on the optical fiber in digital format. The amp unit has a digital signal processor that decodes whatever the head unit is sending into up to 4 channels, plus center speaker and sub-woofer, amplifies them and drives the speaker cones. The subwoofer has it's own amplifier module built into it. All the rest are done by class-D chips in the amp module.

It is conceivable that errant commands on the digital bus from a service computer could cause a software error in the amp. The amp hardware is the same across many models, but the software that's loaded into it when the dealer installs it is different. I'd not think it likely though, but it is possible.

There's really no easy to diagnose this stuff. The speakers can be tested at the amp plug with any handy speaker level audio signal. The digital signal is trickier. Try various sources and modes on the head unit. If you can lay hands on a DVD-A audio disk, try that too. (these are not the same DVD movies.).

The only simple diagnostics are substitution. Quickly swapping the amp unit or the head unit with a known good unit would be the sure test.

Popkid

Mine does this temporarily on occasion, usually after stopping after a reasonably long drive then restarting shortly afterwards, but it comes back after leaving it for a few hours, pulling and replacing the fuse for the Bose (in footwell fuse box) makes it come back straight away. Did you check the fuse yet?

hexagone

Pulling the fuse (was fine) and cycling the car on-off a few hours later seemed to do it ... until next time

Bruce In Philly

I heard back from Becker in NJ... their response to me, "We can repair that amp, normal cost is between $450 to $600 depending on defect"

I think this is just canned answer. I asked them if they were aware of this issue etc. etc. To which they did not respond.

I do know this is being experienced by other 997.2 owners... not uncommon.

Peace
Bruce in Philly

Bruce In Philly

You can make it happen pretty easily.... next time you are on the highway for a ... oh say 1/2 hour trip, turn it on, and turn it up for the duration. When you get to your destination, turn the unit off by pressing the power button. Then turn it back on. It should be dead. 20 mnnts later, it will light up again (when it cools). Tuning your car off, pulling fuse... whatever... nothing will work until it cools.

Peace
Bruce in Philly

vg247

The PCM in my 09’ 997.2 at 35k miles within the last 6 months started to reboot itself at random intervals and would not sync with my Bluetooth. Initially the issue could not be replicated by the dealer since I have an extended warranty on it.

Then finally last December I was able to record a video clip of it rebooting over and over on its own during a 1 hour drive which provided my dealer the evidence they needed to file the claim for insurance warranty.

The PCM was dealer replaced, however now my Bluetooth and GPS works fine BUT I have no AM/FM radio reception...up to date my dealer said the PCM has to be sourced via a refurbished one and they will continue to try to replace another PCM once one becomes available, and see if everything works- it’s been 3 or so months so I’m trying to patiently wait until the dealer notifies me a PCM part arrives. - Quite frustrating