Zingari

Chaps, need your diagnostic assistance on this one.

On a couple of occasions now I have been devoid of ALL electrical power even to auxillaries like the clock etc. It happens when I come to start the car.

Usually turning the key all ignition lights will come up, fuel pump, brake booster etc will begin to prime and then when I go to engage the starter I will either hear the solenoid click, or silence and then ALL electrics will go off - including the clock which will stop!

I will then turn 'off' with the key and try to re-engage the ignition but nothing. I thought that 'fiddling' with the key may have resolved it before but I'm not convinced. Usually after a couple of mins of repeated trying the ignition lights will come on and I'll get the starter solenoid 'click' again and then loss of electrics or it will start as normal.

Any thoughts?

I was thinking it could be the

1) Ignition switch, but why would all ancillary power be lost ie the clock?

2) A poor earth on the battery? Checked this and all looks good

3) Is there some power distribution unit where battery electrics are distributed to car circuits? If so where is it?

4) Could it be the battery itself where a sudden draw of power is temporarily disabling it? I'm thinking the battery is 5yrs old but always on a conditioner when car is not used and never sluggish on cranking the car.

Once the car starts it's fine, everything works and nothing intermittant to suggest loose connections etc.

Any suggestions

Zingari

Any clues guys.

I've read Shreather's book and there is a suggestion that the electrical contacts if not perfect can cause 'a number of electrical issues' but I'm querying if this would knock out all power incl clock etc?

Railmaster.

Earth strap as You suggest? Or how old is the battery? could/should be shot after seven years.

Zingari

I've ordered a new earth strap as most opinion points to this. Battery could be 5yrs+ old but has never been a problem and cranks the car well?

I'm interested to know where the positive leads go from the battery and whether they go to a distribution point. Tracing them from the +ve terminal they go under the spare wheel and then up behind the fuel tank. I'd then expect them to go to the motherboard of the fusebox unless there is something else before then ?

Trying to diagnose it when it's not in fault is a PITA

Derek911

If you get 5 years out of a battery you have got your money's worth. I would buy a new battery.

Zingari

OK I've been spannering today and I've done the following:

1. Lifted out fuseboard and checked main positive 'in' connections. Checked all other wires/connections/fuses/relays all looked OK. Had a general 'wiggle about' but not power disturbance.

2. Decided to whip out the clock and check the contacts on that to make sure they were clean/sound - dont ask me why. Now that was a tight fit and the rubber gaiter holding it in!

3. Removed the battery and earth lead. The twisted lead was to some degree 'ionised', copper still clear running through inner strands but it looked dodgy so it was replaced with a new one. In addition the earth to body connection point was given a good clean, again this and the joining wires (one goes straight to ABS unit) connectors were covered in something so gave them a good wire brush.

4. Wacked on a new 096 battery as I managed to secure one for £41 with a 4yr guarantee, 76Ah and CCA 670A. I'm not convinced there was anything 'wrong' with my old Bosch S4 battery but from my detailed files it shows as being fitted 18.03.2006 @£66.39. Previous to that OPC fitted one in 2000 for the 'bargain' price of £162.10

Next job is to tackle the starter motor connections - clean off and tighten up to see if that sorts it.

Porsche930

Hi 964 enthusiasts, I have been researching this forum and Google other sites but unfortunately not having much success. So I thought to post and see if anyone else has experienced the same issue recently and hopefully identified the culprit.

My 90 C2 Targa has started behaving the same start up electrical problem described in Zingari first post. And it happens only at random.

Sometimes right after I shut down the car (that is ignition key returned to position 0 from driving), I'd like to immediately turn it back to position 2 just to read the gauges and make sure all central warning lights are working and that's when I noticed no electrics present at all at position 2.

This happens only at random - there would be no electrics upon turning the ignition key to position 2 either from right after shut down or from a fresh start. No instrument cluster warning light or sound when this happens. It's exactly liked the battery has been disconnected.

Turning the ignition key back to position 0, then return to position 1 and 2 will eventually work likes a charm. All instrument cluster & central warning lights will come up and sound of relay clicking can be heard. Turn key further to position 3 starter position, car will then start right away and run fine.

I have removed the DME relay from the fuseboard, but the removal did not replicate the no electrics effect on the instrument cluster lights and sound with key at position 3, so I ruled out potential DME relay problem.

Where else do you think to check? Many thanks in advance.

Tony,
SF, CA

Porsche930

Just so I can put my no electrics issue to a closure, I might have accidentally found the culprit. Here is the related post for others future references: https://rennlist.com/forums/964-foru...ally-dead.html

Zingari

Chaps

I thought it useful to update this thread to inform people what appears to have solved my problem. It was the battery to body earth strap that looked to have corroded to a degree that it would cut off all power. A new earth strap (and a new battery for peace of mind) and I've not had any more symptoms.

It's worth changing your earth straps and cleaning the connectors for the little money it costs.