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PCM Troubling Behaviour

C

COD981

Member
It's going to need a new pcm, I had my replaced recently after having similar issues, my navigation would not load, CD wouldn't recognise discs plus a few other things and it started rebooting every few minutes.

Opc tried updating the software but as I suspected it didn't cure it so it was replaced luckily I have an extended warranty

 
I'm hoping it won't come to that, I have no warranty! I haven't checked recently but the CD player was working and the map display too. I haven't checked the navigation. I'll try that when I next have it on. The chrono was working too. Most things are, just not all of the time!

How old was your PCM?

 
I have been experiencing random faults with my PCM unit in my 981 Cayman S since its MOT in March. Nothing was apparent during a warm up drive shortly before the MOT, nor on my drive to the Porsche Centre for the MOT. It would have been driven from the Porsche Centre to an offsite independent test centre.
I think the AM radio was on when I collected it. I would not usually use that wavelength but has defaulted to it since. But technicians do sometimes change things.
The car is kept parked in a dry garage. I noticed a strange noise when I was using the workshop equipment and eventually realised it was coming from the car. The AM radio had switched itself on with no key in the ignition. I had to get key to turn ignition on and off to switch PCM off. This was the first sign of anything wrong with the PCM.
During the first outing since MOT I noticed strange noises from dash area shortly after leaving home. I realised the AM radio had turned itself on again. Stopped to rectify but the buttons didn't seem to be working correctly. The PCM also switched itself off several times and rebooted, each time with radio back on.
Although the car was registered in 2016 and is five years old the use of only 9300 miles is equal to less than one year and I shouldn't have a problem of this kind.
Porsche Centre said they don't disconnect battery or touch anything when service is only MOT. They had no suggestions except to bring car in for them to run diagnostics. I wanted to do some more checks myself first. But with their experience of servicing so many cars they must have some knowledge about this fault.
Two further drives were completed and nothing unusual noted.
Then I drove to Goodwood for a PCGB track day. All okay in the morning. Used the screen, with audio turned off. On way to filling station after lunch the PCM remained off and I couldn't turn it on. Afterwards it was on and off at intervals during the afternoon and on the way home. It seemed to be getting worse!
Back in the garage since then, with a CTEK charger in use, the PCM was working or not at intervals. Sometimes the touchscreen only working, no buttons. I tried a factory reset which made no improvement.
When last driven out of the garage, the PCM came on. Buttons working at random, touchscreen okay. Rebooted itself a few times. Off again when reversing in but camera display working.
Probably too much detail but I'm trying to indicate the apparent randomness of the problem. Has anyone else had a similar experience? The same or a similar unit must be in use on multiple models.
Booked for service visit to Porsche Centre on 27th May.
 
My car is late 2014, some months before it had played up once when the map failed to load until I had been driving for some time, then it all worked OK until the drive when it started rebooting every five minutes or so then the next time I drove it it was rebooting at much shorter intervals, it may be that in your case this is the start of the problem like I had when it was just the map not loading, by the time I took it in it was all over the place loading different things each time I turned it on such as radio coming on when I left it on media and sometimes the volume would be lower than I left it sometimes a lot louder etc

 
Thanks for the link. Interesting to read of all the problems with PCMs, they seem to be very common but all subtly different except for being expensive to fix. And of course PCMs are common to all models. I don't think it fits well with the Porsche brand image of technology-driven. I'll add my experience to that posting when I have some more to report.

 
This is my update after a visit to the Porsche Service Centre today.

I did a test drive yesterday to check on the latest situation. On start-up the PCM display came on & I was able to use the Nav & Map. Only the touch screen worked, no buttons. This lasted for about 5 miles before the screen went black. But the Nav continued to operate on the dash instrument.

Today I started up & the same thing happened. But this time everything on the PCM was working. All functions, touch screen & buttons. This lasted for 20 miles or 30 minutes before it went black for the rest of the journey.

The Centre had it all day but reported they had been unable to connect to it with their test equipment so were could not identify the fault. So all they can offer is to replace the complete unit. I will probably try an independent next. Any recommendations in the Sussex area?

 
Cartronics in West Byfleet are very good, I realise they maybe a few miles away from you but they know their stuff and should be able to sort your problem.

[link]https://www.cartronics.co.uk/our-work[/url]

 
Hey I have been talking to people about upgrading the pcm 3.1 and allowing autoplay. So I got the instructions/ destructions! And read through the installation and it looks straightforward enough.

My point being that all the points made in the installation instructions explicitly states to take special care with the ribbon connections etc to the pub boards. The troubleshoot has many examples of issues and resolves to them. My suggestion is to simply remove the pcm from the dash and simply open it up and inspect the connections as these symptoms sound classic of a Loose connection.

Also of course the porsche dealer can't connect to it if its lost its connection inside. Worth a try. Free and conclusive.

Cheers Q

 
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