I have determined and implemented the fix for the 'lost time' or 'incorrect time' or 'can't change the time' problem due to battery disconnection on porsche vehicles. I used this routine on my 2011 Panamera. The incorrect and locked-up time was caused by the GPS losing sync. The car would not update the time. I could not adjust it manually in the instrument cluster (steering wheel controls) or the PCM unit menus.

What you need: PIWIS system or an advanced coder, not a simple reset or OBD unit. I heard some people got a grey market PIWIS III setup on a torrent. They ordered the OBD interface module from Aliexpress. They operated the PIWIS within a VMWARE virtual environment. You can read about this process on Rennlist, google it. It's certainly a whole project in itself.

On my PIWIS III setup, I used these steps.
Enter the german-language diagnostic mode.
Go to 'Overview' page (top menu, first button)
Select F7 to choose 'Add'l Menu'.
Select 'Maintenance Vehicle Data' on the function listing.
Hit F12 through a few pages (I had to hit five pages) until you see the 'M numbers' category listed in the Value Group column. You will see the active and existing modules because they have entries in the Value column. I hit the column header 'Value' to sort the active modules at the top.
You need to change the following three settings to make the car think you don't have NAV/SAT:
#1: SAT-RADIOEMPFANG. On mine, I changed it from 686 to 688.
#2: NAVIGATION PCM. On mine, I changed it from 672 to 7T1.
#3: RADIOS. On mine, I changed it from 665 to 609.
(Write down your original installed module codes.)
Next, hit F12 two times until you see what looks like a table of changes.
Hit F8 (SAVE).

Hit F11 a couple time to go back to the main modules overview list.
Select EACH of the KOMBIINSTRUMENT and the HEADUNIT modules so they are both highlighted.
Hit the Coding Programming menu item at the top menu.
(***Make sure your car battery and laptop batteries are on chargers and have good voltage levels. Don't disrupt the process, the connections, etc.***)
Select 'Automatic coding'.
Hit F12
Observe the progress of the coding.
Check the final status; if one module was not successful then do the coding action again.
If the coding feedback did not indicate any errors, hit F12.

At this point, your instrument should appear to have its display choices reset.
You might need to cycle the key off-on.
Use the functions to set the time and date manually!

Now repeat this process and code the three changed items back to their original module codes.
Don't forget to choose both KOMBI and HEADUNIT for the auto code setup.

You should be done and have correct times now!
Good luck!

 

Hi,

So I did something similar the other day but with less steps and the same end result. I used PIWIS from a link I found elsewhere in a VMWare image and a generic VAS6154 V1.66 box from AliExpress (Around £40 shipped). I wouldn't really call it a project in itself if you buy the right things, download the files, and have some experience with tech. Once I had the bits it took about 30 minutes to get it setup and working.

I didn't need to tell any module other than the instrument cluster (KOMBIINSTRUMENT) that it didn't have satnav. In KOMBIINSTRUMENT Manual Coding I just set NAVIGATION PCM from 672 to a not fitted option and coded it. Instantly the dash let me manually set the date and time. Once this was done I re-coded it back to 672 (navigation installed) and the whole CAN network updated with the correct time. Up until then the gateway had just seen invalid time so wouldn't show anything in the cluster and showed the complete wrong time on the PCM and Chrono. As soon as it had a plausible time it rippled the change through the CAN network and the time has remained correct ever since.

Out of interest why did you set the other values?

Many thanks!

 

I was blasting all the head unit modules trying to make it work. But like you said,I think just telling kombi there is no unit was adequate. That was the first time that I included kombi in the coding vs just the head unit.