purrybonker

Drove my '06 across town yesterday after it had been sitting in the garage for a few days. 45 minutes of mid-day traffic - some idling, but some runs up to 50 mph or so. Stop at bank, run into ATM - back to car - DEAD battery.

Well, not completely dead - engine spins in one of those "wuh.... wuh... wuh" death thralls, you know the sound. Radio, electronics all work. 1-800 Porsche, tow truck and boost - on my way in 15 minutes.

Phone dealer to let them know I'm coming. On arrival they diagnose an (apparently, not uncommon) alternator cable fault that allows a short-to-ground and inadequate charge to the battery. Four hour job requiring intake manifold removal.

Wow - I had noticed that the car seemed to crank a bit slow from time-to-time, but with a recently CPO'd, low miles '06 car - I hadn't thought too much about it.

Watch for this boys and girls.

JimG

My car has done this many times but just barely starts. Only does it when the engine is hot. In fact it is at the dealer now because they had to replace the wiring harness and some sending units. This has taken 5 days so far and they have had to drop the engine to get at the wiring. The had previously misdiagnosed this as a weak battery, I am on the 3rd battery so far. I am not a happy camper about this.

purrybonker

Yeah, I'm quite impressed with the dealer - they immediately suspected the harness and were hesitant to just replace the battery. I initially argued with them a bit because I didn't want the car tied up over night. Good thing they won the debate.

Mine was like yours, the car seemed to crank slowly only when hot.

JimG

I just got the car back, it took 5 days for them to get it fixed. After they replaced part of the harness they found a few solenoids fried which added more time. I wonder what will be next.

vitman

I had it happen on my 2006 997S with slow hot starts when the car had about 15K miles. They replaced the harness after several initial efforts failed. Once the harness was replaced the problem went away......until recently. I suggested the problem may be the harness again. They inisist that it isn't the same problem and just replaced the alternator, which helped but the starts don't seem "quite right". I'm thinking that the harness may need to be replaced again. Has anyone had this happen twice? I was thinking about keeping this car for about 20 years but now I'm a little concerned about keeping it past the warranty.

useridchallenged

My 2005 C2 went out of warranty long ago (I have 70k miles now). Does anyone have any idea how something as basic as a harness can fail? Wires don't just go bad, do they? Or is this harness badly designed or badly located (mechanical friction, excessive heat)? My dealer is saying that I should replace the B+ harness ($860) and if that doesn't fix it, then the alternator ($1050). Still not as painful as my 2000 BMW 740i Sport which was in the shop every 6 weeks (not exagerating) and each repair more expensive than any repair I've done on the Porsche. The problem with the B+ harness surfaced because my Nav would get completely lost (wrong location), so I brought the car in for that. The service manager noticed the slow cranking, and said that a significant voltage drop can cause the Nav/PCM to reset itself, resulting in the Nav unit being completely "lost" until it recalibrates itself. I asked the dealer if there was any danger to the car by driving it with the faulty harness, and he said "none". So I'm going to research all this before dropping the $860 on the problem.

purrybonker

My work order says:

"Found bulitin (sic) instructing to check for voltage drop from alternator to battery.... tested power at battery measured to 12.58v measured power at alt with same ground location found 13.8v. Inspected cable where connects at starter motor. Found cable melted at starter motor. Req new cable as per bulitin (sic)...."

So obviously there's a factory bulletin on this that explains the circumstances of the failure. Perhaps that'll help you with your research.

Pete Lech

I just had the cable replaced. Car has only 15K miles on it, but Porsche would only warranty 50% of the cost - I am still out $500. Was this a hidden recall? I noticed when I brought the car in that there were several bulletin items (reprogram PCM software, R & R coolant hose and refrigerant pressure line) that they fixed but apparently were not important enough to call me about.

That is the disadvantage of doing your own service/oil changes - you don't find out about these things.

LlBr

You know those $600 fluid changes some of us endure? While they're at it and car's on lift and hood's open they're supposed to check other stuff, tighten bolts, belt, ckeck for lose wires, review the TSBs for the car etc. If I found out my dealer service was not doing that stuff I would be so p*ssed. Should your alternator cable have been checked?

Pete Lech

Checked my records, previous dealer service was Jan 2009. Judging by the 2008 dates of the comments above, it appears that the dealer missed the bulletin. Does anyone have a copy of it?

Edgy01

If you stay current with a factory trained mechanic you can still have all that stuff monitored periodically. The melting of that starter cable can be due to an improper torque setting where things were allowed (for some time) to arc and ultimate fail. I see that as a latent defect.