Electrical Problem

[j911brick]

A friend of mine who is not on the forum sent this to me. He is out of my area so I can't even look at the car my self. I called another friend who is a master dealer tech and his only suggestion was the alarm box. Anybody ever seen this kind of problem?

Does anyone have any ideas for what is causing my electrical problems? The car is a 2005 Carrera S (Sport Chrono, navigation for PCM, Bose surround sound, sport/heated seats); it was purchased used in 2006 with about 3,000 miles, and now has about 25,000 miles.



There has been an electrical problem since I purchased it. I’m not too surprised that I had trouble keeping the battery charged because it isn’t driven enough, but the battery problems did not seem to correlate very closely to how little the car was driven. In a nutshell, my sense was that I’d get about 6 months usage on a new battery before experiencing weak battery problems and then the problem would worse until it eventually left me stranded when the battery was about a year old … and the battery would need to be replaced. The original dealer claimed they looked at the charging system and it was fine … the problem was likely infrequent driving. So I accepted the situation since this seems to be a common problem with the newer cars.



About a year ago I gave up on Porsche batteries, put in an Interstate battery and started using the Porsche trickle charger. But sure enough, a few weeks ago the battery died again … but there was no warning this time and the car had been driven frequently in the couple days before, including a 120 mile round trip. There was no warning this time and I had just driven the care several time in the prior days (including a 120 mile round trip).



I replaced the batter (Sears Diehard) and then notice unusual problems. But perhaps 3 out of 4 times the car was started there were strange condition … the instrument panel would go blank for a second or so, the clock would reset, the gas gauge might or might not be correct (e.g. show ¼ tank when it was full) and the hazard lights would be flashing.



The original dealer has sold their Porsche business, so the car was given to the new dealer who checked out the car and found an electrical drain. They replaced the alternator harness and found a burnt wire on the harness. The car seemed fine, but upon re-testing they found that about 1 out of 10 times they started the car, the strange conditions returned. These strange conditions arose whether the car was restarted quickly or after sitting for hours between starting.



They have now switched my ignition switch and instrument cluster with another similar car, but the problem stayed with my car. Any ideas or suggestions for where to look next?

[FPB111]

you should also post this on renntech.org and rennlist.com
both get more 996 exposure

[j911brick]

Originally Posted by FPB111

you should also post this on renntech.org and rennlist.com
both get more 996 exposure

Thanks for your input but I don't think I can joint yet another forum. I was on rennlist since day one (literally) but it seems like it went downhill when john sold it.

[Hurdigurdiman]

My 99 C2 had an electrical prob from first buying. The inside lights, doorlights and petrol door all not working. Although I could put the inside lights on manually. I searched for 18 months and eventually found from a forum that the Alarm Modual had in fact 'slipped back into transit mode' .. I took it to a porsche dealer who ran the Porsche diagnostic testers on it. I told them to look in the special menu (i got that info from a forum) of the alarm modual under the drivers seat and take it out of transit mode. They did and all started working as normal. That cost me $80 at the main Porsche garage in Lancaster PA. Ring Porsche and ask them how much it would cost for them to run their testers on your alarm modual. It could be that at fault as your Master Dealer friend suggested.

[bell]

I will almost guarantee you the problem is the harness that is between the alternator/starter/post on side of transmission.
There was a manufacturing problem with these harnesses and they will fail at the terminals.
I have changed quite a few....
With the car running and a freshly charged battery check the voltage at the alt, then the starter, then the post on the side of the Trans, if its voltage is any more than .5 of a volt difference to what is showing on the battery then that's the cure.......it is a pain to change without pulling the intake, but doable with a lift and small arms.....

[Nostril Cheese]

Originally Posted by bell

I will almost guarantee you the problem is the harness that is between the alternator/starter/post on side of transmission.
There was a manufacturing problem with these harnesses and they will fail at the terminals.
I have changed quite a few....
With the car running and a freshly charged battery check the voltage at the alt, then the starter, then the post on the side of the Trans, if its voltage is any more than .5 of a volt difference to what is showing on the battery then that's the cure.......it is a pain to change without pulling the intake, but doable with a lift and small arms.....

This.. I've seen this problem on two cars.

Also, get rid of the trickle charger.

[Uwon]

Ditto Bell and Nostril Cheese.
Had similar problem with my 2006 C2S but fortunately harness was replaced under warranty. Got rid of Porsche battery which had been replaced under warranty and got one from Walmart- have never recharged in over a year and the car sat inside for most of last winter.
Good luck, best of the season......