Jump to content

The RennTech.org community is Member supported!  Please consider an ANNUAL donation to help keep this site operating.
Click here to Donate

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

My PCM2.1 unit is suffering from groundhog day...not funny...

Recommended Posts

My car's PCM unit is showing strange memory anomalies and the dealer simply says "you need a new unit" which I think is a cop-out.


The unit works perfectly (including navigation) except:


1. It always thinks it's summer time (adds one hour). When I go into PCM Settings to untick summer time, the car's clock clicks back one hour and is fine for the rest of the journey, but after the ignition key has been removed and re-inserted and the car re-started, summertime is back.  This happens all year round.


2. The always thinks the "last destination" for navigation is always shown as one particular destination that I once drove ages ago in High Wycombe. The navigation otherwise works fine (I can enter a new address and it works) but the "last destination" always shows as that place in High Wycombe no matter where I last asked the system to navigate to.


3. I cannot store any new destinations.  They simply don't store although the PCM unit issues no error message when I tell it to store the destination.


4. If I delete all the stored destinations in the PCM unit, one at a time, until they are all gone, if I then turn off the engine, take the key out and then turn the car on again, all the deleted destinations magically reappear!


The above errors are really annoying, especially the fact that I can't store any new destinations, including the true "last destination".


I have a Dension Gateway 500 unit in the car, connected to the PCM unit, but the dealer disconnected it when testing the PCM unit and he still couldn't make the problems go away. The Dension unit is working fine - iPod connection in place of the Porsche remote CD player, and bluetooth phone.


I am particularly puzzled as to where the unit is storing the deleted destinations so that it can restore them again on the next start-up!


Any ideas anyone?


Thanks in advance



London, England.

Link to comment
Share on other sites

  • Moderators

Thanks for your reply - what is a PIWIS unit?


PIWIS ( Porsche Integrated Workshop Information System) is the name for Porsche's computer diagnostic system, it is capable of analyzing every system in the car and resetting various systems when they act up or need to be replaced.  All dealers and many independent shops have them.

Link to comment
Share on other sites

  • Moderators

Thanks.... If that's standard Porsche diagnostic equipment I rather think that the dealer must have tried that by now, but I'll nudge them.  Thanks.


Check with them and ask if they did a PIWIS reset of the system, you may find that they did not and just wrote the PCM off as needing replacement.  The reset only takes a few min. of diagnostic time, which has got to be one Hell of a lot cheaper than a new unit.

Link to comment
Share on other sites

  • 3 weeks later...

Nothing has worked, sadly : the dealer can offer no solution except to replace the PCM unit and a 1,4,8 re-boot did nothing to cure the bug.  Pity.


I think I'll live with it.  A replacement is too expensive in the circumstances.


Thanks for your help everyone.



Link to comment
Share on other sites

  • 3 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.