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My PCM would reset itself intermittently ever since I got the car. Sometimes it would happen once a week and sometimes it would be every 5 min. My local dealer has looked at it several times and each time Porsche NA has suggested anything from replacement of the USB connection interface to further testing to try to isolate the cause. It seemed like the HD radio was something that was involved. I disabled HD radio for awhile and the problem seemed to disappear but not using a feature that I paid extra for is not an acceptable solution. I turned it back on and the problem came back. I tried using different USB drives, loading different files and nothing seemed to work.

I was finally notified by my local dealer that Porsche NA has agreed to replace the entire PCM. Hopefully this solves it. I've been delaying my stereo upgrade to try to get this resolved before I start touching the system. I plan to keep the PCM as the source and replace just about everything else except the rear speakers.
 

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Let us know how it goes at the dealer with the PCM replacement. I’ve only had one or two resets since my BS was new. Hope your issues are finally resolved!
 

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You didn't mention which version of software you have. I had a similar problem and Porsche updated the software. I think it is up to 4.76 now. That solved my problem. No more resets.
 

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You didn't mention which version of software you have. I had a similar problem and Porsche updated the software. I think it is up to 4.76 now. That solved my problem. No more resets.
I'm not sure exactly which version of the software I was on but I know they updated once and I asked them about any new updates this time and they said there weren't any so I'm assuming it was up to date.
 

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I've had a few resets on my 2016 Cayman GTS using version 4.76 (current version). At least one or two of these seem to be tied to navigating an iPod Classic menu. Curious to hear how you make out. Good luck.
 

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Discussion Starter #6
Update: I've had the replacement PCM for about a month now and the resets continue with about the same frequency as they did before the PCM replacement. My local dealer seems to be stuck and has tried to point to the files on the USB being corrupt as the cause. The problem with that is its not always the USB source that is playing when the reset happens. I've been keeping a log of when the resets happen and what I'm doing when the reset happens. I see two common scenarios so far. The first is when parking and the parking sensors are activated. I'd say about 75% of the resets happen in this scenario regardless of the source being USB or radio. As soon as the sensor is activated, the PCM resets. I'd doesn't happen everytime I activate the sensors as I do it at home every day but it always seems to be more of a morning occurrence when I'm parking at my office.

The second scenario is just driving at highway speed and the PCM will randomly reset. This typically only happens when the USB is the source and when this happens the PCM will typically freak out. After resetting, if I try to use the USB again, it will rest again within a minute no matter what file is in use. This symptom doesn't go away until I turn off the car for an extended period of time (a few hours).

I'm at a loss of what could be happening. I don't know what is causing the reset so its hard to diagnose. I've asked my service advisor if he could find out if their diagnostic software knows where the reset is being originated from. Is it internal to the PCM or is it external like an intermittent loss of 12V power due to a partial short circuit or maybe even a CAN bus error. I'm not sure if the software has that capability or if they would even bother to check. Just waiting to hear back from him on this. If they can't fix it, I'm inclined to just replace it with an aftermarket unit but I'd want to make sure the problem is internal to the PCM before I do that. If it's external, even the aftermarket unit might not solve the problem.
 

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Have you tried not using USB at all for a week or so?

I use iPod and am on the latest version, it has never reset in use but I've seen the Porsche logo on start a couple of times. However, my iPod classic is used and crashes when it is very hot occasionally.
 

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Discussion Starter #8
I tried it for about 4 days and I still had1-2 resets. The USB was stll plugged in but just not selected as a source. I never tried just leaving it out.
 

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Hate to revive an old thread, but last week my PCM (3.1, 2014 Cayman S) was on the fritz. The Nav stopped working, and the unit kept rebooting every 5-10 minutes. I tried "resetting" it by pulling the fuse for 30 minutes or so, but that didn't resolve the issue. I then tried re-applying the 4.76 update via the DVD, but the update would fail about 90% of the way through with an error that it couldn't write files, and then the system just kept rebooting in to emergency update mode.

As a hail marry, I pulled out the drive (it's a 100GB sata 2.5 inch drive located at the top of the unit.) to see if I could get my pc to at least see it. Sure enough I was able to see the partitions, so I ran some diagnostics on it. These came up with bad blocks.

I ran down to Best Buy and grabbed a 120 gb PNY solid state drive off the shelf for $20. Using Clonezilla, I cloned the failing drive to the new SSD. There were a few bad blocks on the old drive, but it was mostly successful. I was primarily trying to get the boot sector anyway. Inserted the cloned SSD into the unit and bench booted it. It did boot into emergency update mode again (I suspected it would), but I popped the update disc in figuring "what's the worst that could happen?"

The update ran completely and successfully! I popped the entire unit back in the car and everything works flawlessly. It didn't copy over my jukebox files, but the nav, saved destinations, phone settings, presets, and even my lap recordings all copied over. Overall the unit seems a little quicker and more responsive - likely as a result of the SSD - and I suspect the SSD will be more reliable as it's less sensitive to vibration and heat than the traditional drive that was in there.
 

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Thanks a ton for that update. Now at least we know there may be a possible fix. Where did you get the update DVD?
 

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Contacted MaxMotorsports today 5/29/2020 and they no longer sell the 3.1 PCM 4.76 Update DVD because it is no longer available from Porsche. jslo73 really did the community a BIG service by pioneering this FIX for the never ending Porsche/Bose/Harman hard disk problem!
 
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