Alright folks, here's a head scratcher for all of you. My 1987 3.2 has sprouted some electrical gremlins out of no where. All the auxiliaries work and when I turn the ignition on all the dummy lights and gauges come to life. But as soon as I turn the key to the start position, everything dies. No lights, no power locks, nothing. If I disconnect and reconnect the battery, or if I let the car sit over night, everything comes back to life. Sometimes the car starts without any issue. Last night it didn't and is now sitting in a parking lot. My guess is that there is a bad relay somewhere and it must be close to the battery as it shuts down everything in the car. Has anyone ever had something similar happen or any ideas on what might be the cause? Is there a relay that I should go after?

 

Sounds like the ignition switch to me. I see that happen on Honda Civics all the time. Could happen to these cars too. Guys with far more experience will chime in. Welcome. :cheers.

 

But would a bad ignition switch also kill my electric locks and cabin lights?

 

I am not 100% certain Porsche ignition switches cut power to everything else, but lot's of other cars do. Every ounce of juice is needed for the starter.

I'll go look at the schematic.

Actually, I see what you are saying. No they wouldn't. I think that kind of small item likely always has power.

Could be a grounding issue. Is your battery clean and tight?

 

+1
Amber Lamps may be on to something. I had your exact symptoms.

I disconnected my battery recently and thought I connected it back. The cables were on the terminal posts, but not tightened. Everything worked in the car, except it would not come close or even pretend to turn over.

The error was discovered when I went back through to check the Trickle Charger connections. The battery cable lifted straight off. A few righty tighty turns and the car fired at first contact.

I hope this is your issue.

 

The plot thickens. I went to try and start the car tonight. The cabin lights would come on, but at the first switch of the ignition, everything died and the dummy lights never even came on. So I hooked up the jumper cables and I had power and when I tried to start it got about a half crank before everything died again. Getting closer! Seems like my battery is completely dead. I'll let it sit on the trickle charger for a day or two and then see if I can get the car started. I find it odd that the car wouldn't start with jumper cables hooked up...

 

After letting the battery sit all night on the trickle charger, the car started right away. I checked the voltage while running and had 13.8V at the battery. All the dummy lights came on too before cranking. So the alternator seems to be working fine. I'll check the ground straps in the daylight. But now my guess would be a short somewhere that is draining the battery when the car is parked. Thanks for the help so far!

 

FWIW, really carefully check the alternator... had exactly the same symptoms.

Check carefully: when you first turn the key, does the Battery light come on? if it doesn't, that means the alternator is bad. Easy to miss, because after you start the car, they all go off quickly.

Good luck!