Porsche Enthusiasts Club Forum

This little problem has cropped up before and I thought I had it solved - obviously not .

What happens is this...Open car door (a good start), see that the interior light comes on fine. Insert key and turn, all usual lights come up on dash, volts looking fine. Turn key to start, starter goes ugh..click, then all the lights go off and the car is completely dead. Everything is dead, it is as if the battery is completely disconnected. The remote locking doesn't work, the interior lights don't work, the boot release, and so on .

Then, leave it for a while, go back (having not touched anything), and it starts fine...weird or what?

My first thoughts were an internal battery fault or a major wiring problem. I checked the battery terminal posts and they are clean, the terminal fittings are nice and tight. The earth cable is clean where it bolts into the chassis, the chassis brass pad is clean, the bolt and washer is nice and bright. Last time this happened I thought it was the strap and so cleaned the gunky earth pad - it was not too good, and replaced the bolt, etc. That seemed to cure the problem...but perhaps not. However, this problem has not happened for quite a while now.

The starter has been recently re-furbed at a local auto-electrician and turns fine, no nasty noises, etc. the car usually fires after the first turn or two, the volts read 12 not running, and 14 when running, so that looks OK.

If it was the ignition switch I would wonder why all the auxiliary circuits go dead too as they are not routed through the switch. If it was the starter I would expect only that to click and the lights to dim - not go out entirely.

Has anyone else had a similar problem, or could shed some light here? I am a fully-qualified electronic engineer and at the moment this has me a bit stumped.

Back to pouring over the wiring diagrams again...

Im rushing but this sounds like a flat battery.

If I'm not mistaken the power circuit goes from battery to starter motor first then from there up into the alternator and the windscreen scuttle, from there then powers the rest of the car.

Well it does on my 968

I would also say it sounds like a dead battery.

My S2 behaved exactly like that when left for 5 weeks over the winter.

A few days on the ctek charger and it started 1st time and has done ever since.

Check the main terminal on the starter.

Regards a flat battery, it doesn't behave like any 'flat' I have experienced. Everything appears fine, then turn the key and it is totally dead after an attempt to turn and a click. Not just dim, it's a total cut-out as if a switch had been thrown. Then, leave it for a while '20 mins' or so...return to the car and it's all good, no problems at all. I have never heard of a lead-acid cell recovering to that degree so fast, that's why I am puzzled. The cable from the battery does go straight to the starter terminal, so I will have a look at that for corrosion, etc. Car started fine today, 5 times - no problems..?

got to be a loose or naff connection somewhere

Dodgy connector on ignition switch?

Exactly...!

I had already looked at the battery to chassis earthing lead and cleaned the chassis end, I did not expect any issue with the other. However, I had the hatch open today and wanted to start the car (which had been behaving itself), ugh - click - totally dead again. So, out with the voltmeter straight across the battery posts, it read 11.95V constant. Went across the lead battery connectors, it was the same. Went from the +ve terminal to the chassis earth point - 0V.. .

Went up the copper cable with the voltmeter probe - 0V all the way until I touched the lead terminal connector. So, it appeared the problem lay in the crimp connection between the copper cable and the lead terminal connector. Gave it a decent wiggle, there was a little 'crackle' and the lights all came back up...result!

So, the problem is the cable has failed, probably due to years of oxidisation within the joint. As a temp measure I have run a parallel earthing strap across this cable while I order a new one..happy bunny now as it is MOT day tomorrow and I didn't want it playing up.