Car does not turn over

Hi All, Question to the hive mind that is 911UK. My 996 Targa has recently developed a fault where the engine will (not always) turn over in the start position. What happens is that it just does nothing, all dashboard lights stay on, no clicking of relays etc. Then occasionally on turning the key it would cut in and spin at normal speed If I add my booster battery it has so far always started. A couple of times I also appeared to 'help it' by switching off the fans/air con before turning the key. Thinking it was just a battery at the end of its life (it was 6 years old) I swapped it over to a brand new one. After a few weeks its back to what it was before. Car is left permanently on a CTEK trickle charger which is saying battery is fine. When I measured the battery this morning after taking the charger off it was showing 12.3 Volts, which seemed a bit low. I have now swapped in my old CTEK charger to see if this charges it to a higher level and I will re measure tomorrow. It has had a secondary fault with something stuck in the fan assembly making a ticking noise - you can only hear this just before you start the car when on ignition. I thought it was the CD in the PCCM but its definitely something in the fan. I think this is unconnected. The noises has been there for a while. So thoughts? Ignition switch, starter motor relay, alternator/voltage regulator, wiring to starter? Car gets little use but has been good as gold in the 15 years I have had it, other than consuming batteries. I'd add car had been on a long drive after fitting the new battery before I put it back on the CTEK 2 weeks ago, and the fault appeared when I was trying to get it out of the garage to wash it. Cheers Dave

2005 C4S - same problem Hi Dave I have a 2005 C4S - same problem. Back in March I started to have intermittent starting failure. Central locking, lights, radio etc. all working OK, but nothing when I turn the ignition. I changed the key fob batteries and main battery first. No improvement. Then changed the - & + battery cables. No improvement. I called the AA, and the engineer said it was starter motor. He got the car going and I drove directly to Porsche Tonbridge, where they replaced the starter motor. The car still won't start every time. Battery is showing plenty of juice. The Porsche workshop are scratching their heads. Been 2 months of agony now. Next steps will be testing the ignition switch, starter motor relay and alternator. So unless anyone else has an idea, I guess I'll keep throwing money at Porsche. I'll let you know if we get anywhere. Cheers Paul

Try either the ignition switch or the clutch switch on pedal if its a manual. The clutch pedal switch can be easily by passed and the ignition switch can be tested if you a ohms meter.

Re: 2005 C4S - same problem Sorry to hear that, does sound very similar. In my case it started after my last fill up, when it took a second go which I put down at the time as me ytyring to start the car while it was dig the 5 seconds to oil level reading thing.

Thanks for that advice. Yes its a manual so I'll try the clutch switch first. I'll also look at how to test the ignition switch (I have a basic multimeter)

could be the ignition switch, but might also be worth looking at the "Y" cable. See http://911uk.com/viewtopic.php?t=138333

I had the same problems quite a few years ago and I changed the starter motor and the ignition switch At the time it seemed to be an issue with 996 so I got 2 of them and carry one in the car just in case and so far so good Hope this helps

If the dash lights don't go dim or off then the starter is not drawing any current, so not battery problem and probably not starter. Could be one of the switches mentioned already or possibly a bad live or earth connection somewhere between battery and starter which is only showing up with high current demand. I have read here about issues with the battery earth connection to the chassis, behind the battery and to the left side of the car.

For the battery voltage, should be up towards 12.9 0r 13 volts fully charged, no load,(i.e. when the CTEK says its full), and always about 14,2 with the engine running and alternator charging, even if the battery is dying or not chatged, so there are a couple more things for you to chack.

I'm very surprised Tonbridge are struggling .. perhaps i should give them a call as they are our local supplier for parts lol .. As below .. there is a relay for the starter .. i would replace this or use it as a test area to find the fault .. if it doesn't start and you have term 85/86 as earth / 12 volts .. you have term 30 as 12 volts then its the starter or wiring to starter . Any of the above and backtrack on what's missing . Start lock relay pos 7. which is behind the rear seats and under a carpet/panel unless you have a cab Pretty simple diagnostics to be honest .

Fixed Ignition stater switch. £12 fix :thumbs:

Sorry for delay in replying. It took me a while to get it booked in at an Indy and during this time I noticed another fault, this time the alternator not charging by the end of a journey (seemed to be OK when cold). This explained why the battery was loosing charge. Indy has now changed the alternator and no other faults found, so lets see if that was it... lets hope so. Dave

If it doesn't turn over at all having been on a trickle charger, I can't see how an alternator fault would cause it not to even try to start. My money is on the ignition switch being on it's way out, and I would change it as a matter of course as a known weak point - thankfully a cheap part and easy to change.

To me it sounds like a classic ignition switch fault? I wrote up how to remove and fit a new one somewhere on here, it was reasonably easy, I just can't find it at the moment?

https://www.911uk.com/viewtopic.php?p=1642130