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964 Tiptronic Electrical Issues

Dazzler911

Dazzler911

PCGB Member
Member
Hi,

i just wondered if anyone can offer some advice regarding my 964.
Its had a starting issue for a while but I've always managed to get it going. It basically used to just click on the turn of the key with no attempt to crank. A few tries later and it would spin over. I changed the DME relay which seemed to cure it for a while until one morning it wouldn't go at all. Eventually it did with a starter pack on the battery and I drove it down to 9excellence who were due to do an oil change. Subsequently they couldn't start it and changed the starter motor and battery but the problem still exists although now it doesn't even click like it used to. It's just dead when you turn the key. To compound the issue its now stuck in limp home mode, the new battery doesn't seem to be charging and it got very hot driving home (transmission stuck in 3rd maybe cause it to get hot?). Now before it went to the garage the only issue was starting so I'm wondering if any wiring has been disturbed by them changing the starter as the gear change was fine before it went in. The oil pressure and temperature gauges were also jumping around and that has never happened before too. Anyone have any ideas ?
Thanks
Darren
 
If you have paid someone to fix it and the problem still exists and appears to be actually worse, I think your first port of call is the garage in question.
 
I agree with Colin. Personally I'd be livid if a garage had done that to me. For a start they obviously haven't done any diagnostic work and just replaced a bunch of parts.
Unfortunately it is all to common.
I heard from a member who'd spent over £1k on a garage replacing parts on a hope it'll fix it attitude.
It eventually turned out to be a loose wiring connection.
 
Yes I have gone back to them so I'm hoping they will sort it out. The bill was £905 and they wanted to rebuild the engine due to the oil leaks. They did a compression check and it's down to 120psi on 2 cylinders but it runs fine, well it did before it went there. Apparently the boss is away at the moment so they can't do much. Not happy.
 
The electrics in the 964 are tempermental and are known for playing up when not used much, I personally describe it's like they are sulking from not being used. The good garages like to swap parts from a working car until the trace the fault rather than constantly replace items as it iust doesn't work.
First check the internet particularily rennlist.
Basic checks distributor caps,rotors,leads.
More obscure earth'strap is fairly common and any earthing points and get them to check for arcing in the engine bay.
 
Electrics have been fine on both my 964's and it's not often you hear of problems.
The only time is when they've been stored a long time or under covers where damp has gotten in, and this affects the earth points mainly.
The wiring diagram shows all the earths and the other main earth points are between the battery and body and the starter and body.
As for arcing in the engine bay, start the motor on a dark night and raise the engine lid, if you see arcing it'll be from the HT circuit and unlikely to be causing the problems you describe.
Starting problems can often be laid at the alarm system, however the change in fault with the new starter and battery sounds like alternator or fan belt issues as it's getting hot, I'm assuming you're talking about the oil temp?
If the garage don't offer to remove the new parts and put back the old ones that are still good, ask for them back. The solenoid also has an earth lead within the cover and is known to oxidise and need replacing. So easily repairable.
Batteries do suddenly lose power, I had one where all the lights came on and when I switched it to start all the lights went out and no solenoid click. I thought it was earth and replaced the battery to body connection as it was well green with oxidation but no change, When I swapped battery for one from my Saab, it starter OK. That's when I knew it was the battery was dud and although a good make, Bosh with 5 yr warranty, it was replaced.
 
The tip-box has a big switch operated by the gear lever; that system has to be adjusted to work properly. Otherwise e. g. "P" won´t engage the internal lock or the engine won´t start as the the signal gearbox in "P" or "N" to make a start possible is not transmitted. At the limit of adjustment it might sometimes work and sometimes not. For a garage that knows the business it´s a matter of 15 min - including jacking the car up.

Might be worth a check, diagnosis from the distance is always difficult. No idea about the issues after the "repair". Sounds like you might need a lawyer or Dirty Harry.
 
To sort this we have adjusted Tip gearbox cables and replaced 'nearly new' starter motors.
Always worth checking flywheel position sender too.
And before any of the above check wiring connections to starter motor!!
Worst case it might be a tiptronic multifunction switch
Good luck.
 
Just an update. The garage have agreed to look at it again. I changed the battery earth cable yesterday as a precaution as I've read these can cause issues, and tried to start it up again. Strangely it cranked over but wouldn't fire, but yet when I released the key from the cranking position on the ignition it then fired up.
Has anyone experiences a faulty ignition switch on their 964 ?
Darren

 
The ignition switch can be shorted to verify it is the problem. You need to be OK with electrical stuff and make your way around a wiring diagram. The starter solenoid is activated from the ignition switch.
+12v is on Terminal 30 and is switched via the key to Terminal 50 which connects to the starter solenoid. So applying +12v to T50 should start the motor turning over. This is what garages should be doing when proving whether a part is faulty or not. It really is just basic common sense.
https://www.dropbox.com/s/5elu16dvxjwdw6z/pdftown.com_porsche_964.zip?dl=0

 
Colin in stereo [:D]
vitesse said:
Which unfortunately is what thieves do when Hot wiring to nick your car-David!
Click to expand...


This will only turn the motor over and not necessarily start it because the ignition circuit is disabled by your burglar alarm, comprende compadre.
 
Update:
New battery fitted.
Car only starts when you release the key and not when cranking. - Ignition switch maybe ?
Tiptronic transmission light comes on as soon as you move and does not change gear. Low fluid maybe ?
Could these issue be related ?
Any ideas appreciated.

Darren

 
Update:
Issue fixed by AW Motorsport, Southbourne, near Chichester
Previous garage (Not the garage above I stress) who looked at it had left off the starter motor earth strap. Although the issue was there prior to this so I suspect it was corroded. Wont be going back there again.
glad to get it all up and running normally. See you all at upcoming meets!
Thanks all for your input along the way.
Darren

 
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