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Discussion Starter #1 (Edited)
Not sure if anyone has experienced this one, but over the past 2 weeks I noticed that my Apple CarPlay was acting glitchy. It would inconsistently connect to my iPhone 6 Plus, and when it would connect and I would launch Spotify, I would pick a song and it wouldn't play unless I unplugged and plugged my iPhone back in and start the connect process all over again. My thought for the past 2 weeks was that this issue was due to me upgrading my iPhone to IOS 10. But today when I got back in my car to run an errand, CarPlay would not connect at all, and google maps would never load. The Google maps loading indication would just sit there. Then it occurred to me, I had glitchy PCM issues with my 981 too.

What I discovered about the PCM in my 981 was that the unit has a hard drive and memory just like the computer sitting on my desk. Unfortunately just like the computer on my desk, it has to be cold booted every now and then. Meaning that the CPU memory had to be cleared out and the software programs need be reloaded back into memory from the hard drive. It would be nice if there was an on and off button, but there is not one. So, to do this on my 981 I had to pull the fuse that was associated with the PCM which shut the hard drive down and cleared the memory of the CPU. I remember when I unplugged the fuse, I heard the hard drive spin down with the car off. When I did this, it immediately corrected my issues and all was right with my PCM.

My first thought today as I sat in my driveway with my 718 was crap, something is wrong with my PCM, then I remembered my 981. So I pulled out the owner's manual went to the fuse section and on page 114 it shows that on the passenger side of the car fuse panel, Row B, fuse number 4 (7.5A) is the fuse associated with the Central CPU. Making sure my car was not on, I pulled it out, waited for about 20 seconds, and put it back in. I started my car and could see that my PCM was reloading it's software, and within seconds, my Google Maps loaded with no issues as well as my Apple CarPlay and noticeably everything was happening much faster.

If you notice that your PCM is just acting odd and not doing what it used to do or is really slow in responding, doing a reboot of the CPU may clear it up. I am willing to bet this is exactly what they would do if take your car to the dealer with PCM issues.
 

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Not sure if anyone has experienced this one, but over the past 2 weeks I noticed that my Apple CarPlay was acting glitchy. It would inconsistently connect to my iPhone 6 Plus, and when it would connect and I would launch Spotify, I would pick a song and it wouldn't play unless I unplugged and plugged my iPhone back in and start the connect process all over again. My thought for the past 2 weeks was that this issue was due to me upgrading my iPhone to IOS 10. But today when I got back in my car to run an errand, CarPlay would not connect at all, and google maps would never load. The Google maps loading indication would just sit there. Then it occurred to me, I had glitchy PCM issues with my 981 too.

What I discovered about the PCM in my 981 was that the unit has a hard drive and memory just like the computer sitting on my desk. Unfortunately just like the computer on my desk, it has to be cold booted every now and then. Meaning that the CPU memory had to be cleared out and the software programs need be reloaded back into memory from the hard drive. It would be nice if there was an on and off button, but there is not one. So, to do this on my 981 I had to pull the fuse that was associated with the PCM which shut the hard drive down and cleared the memory of the CPU. I remember when I unplugged the fuse, I heard the hard drive spin down with the car off. When I did this, it immediately corrected my issues and all was right with my PCM.

My first thought today as I sat in my driveway with my 718 was crap, something is wrong with my PCM, then I remembered my 981. So I pulled out the owner's manual went to the fuse section and on page 114 it shows that on the passenger side of the car fuse panel, Row B, fuse number 4 (7.5A) is the fuse associated with the Central CPU. Making sure my car was not on, I pulled it out, waited for about 20 seconds, and put it back in. I started my car and could see that my PCM was reloading it's software, and within seconds, my Google Maps loaded with no issues as well as my Apple CarPlay and noticeably everything was happening much faster.

If you notice that your PCM is just acting odd and not doing what it used to do or is really slow in responding, doing a reboot of the CPU may clear it up. I am willing to bet this is exactly what they would do if take your car to the dealer with PCM issues.
Very interesting, there was a thread here about what you would expect to see as the PCM booted up, the graphic of your car or the Porsche logo... Do you recall what you saw?

My wife's PCM is acting up, right now the only 'radio' that will work is the XM radio the AM option disappeared and when you select FM it just goes the XM... strange. IF it were not schedule in for Monday I would locate the fuse and pull it, but if there is a chance that the PCM is defective I don't want to 'reset' any of the error conditions that currently exist.

Are we actually sure that the PCM desn't actually do a reboot every once and awhile?
 

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Discussion Starter #4
Very interesting, there was a thread here about what you would expect to see as the PCM booted up, the graphic of your car or the Porsche logo... Do you recall what you saw?

My wife's PCM is acting up, right now the only 'radio' that will work is the XM radio the AM option disappeared and when you select FM it just goes the XM... strange. IF it were not schedule in for Monday I would locate the fuse and pull it, but if there is a chance that the PCM is defective I don't want to 'reset' any of the error conditions that currently exist.

Are we actually sure that the PCM desn't actually do a reboot every once and awhile?
The issue you are describing with your wife's car is exactly what I experienced with my 2013 981. I totally understand why you don't want to pull the fuse and keep the error condition. I will tell you that when my PCM rebooted on both my 981 and my 718, they did show the graphic of the car loading. I am not sure if there is some sort of auto reboot of the PCM. What I am pretty sure of is that all there are all sorts of systems in the car that remain active as long as the battery supplies power to the car even though the engine is not running. By pulling the fuse for the PCM you are effectively clearing the memory and forcing it to do a reboot and reload the software it runs on. This would also happen if you disconnected the battery to the car as well.
 

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Discussion Starter #6
Lomorris, here is the thread I mentioned about the logo/graphic seen on the PCM and hence my question. http://www.planet-9.com/981-cayman-and-boxster-electronics/125994-has-anyone-figured-out-how-why-porsche-crest-appears-start-up.html

Lately I have seen both, see my post.

I am seriously tempted to pull the fuse on my 981 to see the effect... perhaps I will ask when we take the Macan into the dealer on Monday what they think about doing a reset (which may be a part of what they do?).
I just read that post, I totally understand your approach. Pulling the fuse with the car off won't damage anything, but you are correct in that you might lose the error condition. Keep us posted, I would love to know what might cause the erratic PCM behavior. It reminds so much of a desktop computer that needs a cold boot.
 

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Discussion Starter #7
I just read that post, I totally understand your approach. Pulling the fuse with the car off won't damage anything, but you are correct in that you might lose the error condition. Keep us posted, I would love to know what might cause the erratic PCM behavior. It reminds so much of a desktop computer that needs a cold boot.
I also looked in the owners manual and other forums, and can't find any other way to reboot it.
 

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Westcoaster, what was the verdict on the PCM issues you were having. Was it in need of repair?
Hey there, they looked at it and could find no 'physical' or 'hard' fault so they simply reset the PCM with instructions to bring it back if it happens again... I wasn't there to pick up the Macan but will follow up with the tech the next time I see him.

This restored the missing 'AM radio' selection and the ability to actually get to the FM tuner, so essentially back to normal.

Hmmmm, it sure would be nice to know more about that system.
 

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Discussion Starter #10
Hey there, they looked at it and could find no 'physical' or 'hard' fault so they simply reset the PCM with instructions to bring it back if it happens again... I wasn't there to pick up the Macan but will follow up with the tech the next time I see him.

This restored the missing 'AM radio' selection and the ability to actually get to the FM tuner, so essentially back to normal.

Hmmmm, it sure would be nice to know more about that system.
Interesting that they did not tell you exactly what they did to reset the PCM. Pull the fuse maybe....? I would love to know what the tech tells you.
 

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I just had a recall done yesterday.. apologies I don't have the invoice in front of me but it was a PCM and dash software upgrade/reflash.
 

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Still haven't had the time to get down to the dealer to ask how they reset the PCM in the Macan...
 
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