Hello all, I was hoping to get some insight from forum members in regards to problems I have been having and which is now preventing my car from starting all together. My vehicle is a 2007 Porsche 911 turbo with about 66,000 miles. Back in June I went out to start my car (it is not a daily driver and gets driven about every other weekend or less) and it clicked once and then nothing. The windows began rolling down, meaning the car thought the battery was dying. I suspected a dead battery as well and went to Auto Zone to purchase a replacement. Upon reinstalling the battery the car fired right up, and there were no more issues for approximately 3 months. In September the same issue occurred (windows started rolling down again), and I exchanged the battery under warranty and upon installation of the battery it again started right up. For the months leading up to this, every couple of times or so when starting my car after it had sat for a while, the first key turn yielded a failed start. I would release the clutch pedal and press it again and upon the second turn of the key it would start. What I was not paying much attention to was the fact that during the first key turn all electronics would be dimmed when starting; as if the battery were too weak to start the car. Last month I went out to start my car and it again did not start. By now I figured I had a battery drain issue. I tried charging the battery overnight which did not help and the next day I went to exchange it. The store clerk checked the battery and it came up as 12.xx volts. He stated the battery is good and that I may have another issue which may require further investigation. I reinstalled the same battery and this time the car started right up?!?!?! No light flicker or anything. The car drove fine for the next couple of weeks. Now it seemed as if there were a short or some other electrical gremlin prohibiting my car from starting. Last weekend I went to start my car after visiting a friend and nothing at all. There is no cranking and as soon as you turn the key the with the clutch pressed down, all electrics go off, as if there is a major short. I disconnected the battery, and reinstalled it again, but still no change. All electrics go off. We tried push starting it and it started right up. I drove home and parked it and started doing some research. I tested the battery and it is full at 12 volts. Is there is a problem with the starter shorting out the system, or do I just need a new starter? If I put the key to the engine start position, or accessory position there are no issues. It is only when the clutch is pressed and the starter is engaged that the power to the car killed. Could the starter relay be causing this issue? The car gets spark, air, and fuel, because if you push start it there are no issues and the car runs fine. When searching I can't find any forum members that have had issues similar to mine. Any insight would be very helpful.


Thanks for your help and sorry for the lengthy description. If more information is needed for you to help me please ask.

 

Sounds like the clutch switch is the culprit? Worth looking into

 

^ +1... I would check that clutch switch.

Good luck.

DC

 

Thanks all for the prompt responses. I had ruled out the clutch switch because I could not see the switch cutting power to the entire car. I also count not find any posts where people had similar issues as mine when the clutch switch was actually the problem. Nonetheless it is a very cheap and easy part to change so I think I will start there. Does anyone else have any ideas?


This is the part you guys are referring to correct --> http://www.ecstuning.com/ES1494411/


Thanks again for your help.

 

Honestly it sounds like a bad/intermittent ground to me. The clutch switch is completing the circuit that is why you lights are dimming, you just aren't getting enough voltage when the battery is drawn on.

Everytime I have seen that sort of symptoms it has been a bad ground.

 

Correct for the part but rx7 brings up an excellent point about the grounding. There was some discussion about the ground wire from the alternator to the battery that seems to fail.

 

I have read many complaints on the 997TT boards about difficulty starting the car when the battery is good. I have it too. The problem may not be the battery. The best explanation I have found is that one or more of the cables to the starter is defective/worn. I intend to see if this is the fix for my problem at the next service.

 

Thanks all for your help with trying to help me figure this out. As an update I will hopefully be able to check the starter connections on Thursday evening. I went to try and start the car and now when I go to start it all electrics go dead and stay dead for at least 10 seconds before becoming active again. I think this points to a bad ground or a short somewhere in the system. I am hoping a bad ground as I would not know where to start searching if it were a short somewhere in the system. The battery still shows a full 12 volts and I tried a different battery just incase there was a dead cell. This would still show 12 volts but not provide enough power to crank the car. Therefore the battery is not the problem. On Thursday I will also hopefully be able to swap clutch switches with a fellow 911 T friend which will rule that out as well. This will then leave the starter connections and starter as my issues.


I will provide updates on Thursday but will still be reading this post daily to see if there is anything else that anyone else suspects.


Thank you again everyone.

 

Is this the harness that you guys were referring to?


http://www.suncoastparts.com/product/SKU997HARNESS.html

 

With the car manifesting that behavior I would think you could find the bad cable/ground by checking the cabling for signs of heat. Be careful. Sometimes marginal battery cabling can get darn hot.

Check the cabling/grounds.

But consider the ignition switch, too.

 

Agree with the ground issue.

I had a 2003 Z06 that had a similar issue. The source ended up being a bad ground due to a head light modification from the previous owner. It took months to find the culprit. I hope it's something simple like that even it it takes a long time to find.

 

Do I recall reading about ignition security issues and perhaps a failure on that end? Something to do with the key lock mechanism.

On the surface it sounds like a grounding issue to me though.

 

My car is at the dealer right now getting this sorted out.

Replaced so far:

New ignition switch (no fix)
New battery (no fix)
New clutch switch (will see tomorrow)

Next up is replacing the battery cable throughout the car.

I swear ive upgraded half the car this month lol

 

Hope the clutch switch solves it. Perhaps you should also, document any electricial mods to help with the trouble shooting process

 

I should know tonight if the clutch switch fixes it, though I highly doubt it. Also as an update the car has no electrical mods. The only "mods" to the car are the coolant pipes were welded, Sachs 2.5 clutch, GT3 throttle body and 82mm plenum.






Lysol any update on your car? Does my description sounds similar to your issue.