For the cliff notes, scroll down...

So, my battery in my 2008 997.1 turbo cab died. Again. It was replaced by Porsche 5 months ago, stored on a battery tender, and was driven a few times. It only lasted 10 days off the tender before it died again. While jumping it after multiple attempts with a portable jump charger, then my Panamera GTS, it finally started. I drove it around for 40 minutes, went to the grocery store, picked up a few things, and boom - battery dead again. Waited 2 hours for a tow truck that couldn't load it because it was too low. Driver was able to use an industrial jump box and It started. The battery had 12.6 volts on the tow guy's meter before it was started, then immediately began charging to 13.8 volts. I have since driven it home and it is starting now after a night on the battery tender. It's going to the shop this week, and I suspect there may be a starter issue or a bad connection somewhere.

I'm guessing I cranked the car 50 times yesterday between my attempts to start it at my home and in the parking lot. After all of that, now the PCM isn't turning on. The 25A fuse was blown. I swapped it with a reserve fuse and it's still not turning on. I have not checked the fuse on the back of the PCM module, which may also be blown and could be the fix.

Cliff Notes - I have 47k miles on the 2008 997.1 Turbo cabriolet. Manual transmission. It's in pristine condition. The car has the sport chrono system, adaptive seats, and BOSE speakers with sub. I have new untouched replacement seat leather and interior leather trim that I've been holding to make the car "new" again when I'm ready to sell it. Is it worth replacing a broken PCM (the grey one - non touchscreen) to keep it all factory, or would I be better off to install an aftermarket "modern" sound system? Will removing the factory PCM decrease resale value? What functions will I lose if I replace the PCM? I know that the chrono timer, lap timer, and sport mode all appear to be working without the PCM now.

 

Hopefully it's the local PCM fuse (I didn't know there was one).

Has anyone checked for a parasitic draw on the battery? 10 days is pretty short for a battery to give up it's charge (unless the trickle charger wasn't doing it's job).

Has there been any change in where the car has been kept, recent service done or anything that coincides with the battery issue? You'll have to think back to when the 1st battery was replaced.

Ed

 

Fortunately, the fuse was blown. After a simple replacement, it all works now! We're checking the starter system (cable, solenoid, etc). May have an issue there.