PSA - Inspect and clean your positive battery lead connection point at the bulkhead

I was left stranded in the carpark of my local supermarket on the weekend by a complete electrical system shutdown. When I turned the key to start the car, everything died, no dash lights, no interior lights, key stuck in the ignition. I had to use the pin (clipped to the fuse box cover) to remove the key. Luckily I wasn't too far from home and was able to get my wife to come get me so I could pick up some tools from home to try and fix the problem. I checked the battery health, perfectly good and 100% charged (only 18 months old but you never know) Battery terminals looked clean and connections tight Ground lead connection to body looked perfect. All fuses in kick panel were fine Tested the 404 relay in the kick panel, also fine Reconnected the ground cable for the battery and the car (electrically) came back to life, tried to start it and it died again. Tried disconnecting and reconnecting the ground cable after a couple of minutes but nothing, still dead. Oh well, perhaps it needed to sit a bit longer for something to reset? While all this was going on I had been searching the interwebs/forums and also messaged a couple of local 987 owners incase they had ideas I could try there in the supermarket carpark, a lot of those suggestions and interweb theories pointing back to a grounding issue of some sort which is what I was leaning towards. NOTE: a week earlier I had been doing some vigorous back road driving barefoot and noticed during a couple of hard right hand turns that I was getting some cold drips on my foot, it seems that the drain for the AC wasn't doing its job properly. Not sure how long that had gone on for but the passenger footwell was quite damp too. Hence my suspicion of a grounding issue up under the dash somewhere... Just as I was about to contact a tow company, one of my friends found a post in a FB group from someone a couple of hours earlier (spookily close in time to when mine died) describing the exact same symptoms and that it turned out to be the connection point for the positive battery lead to the bulkhead. This is located just beside the battery, the cable connector is black plastic and has a red plastic locking tab on it, you slide the red tab away from the connection and then you can pull the connector off the stud. I bought a pack of brillo pads in the supermarket (one advantage of breaking down there I guess) gave it a scrub, reconnected the lead and was able to start the car again! When I got home I gave the post a more thorough scrub and clean before applying some dielectric grease. This connection post doesn't seem to be all that well protected from atmospheric moisture so I suspect a lot more cars will have some surface corrosion as well, check and clean your rusty posts people!

Great info for us owners of older Porsches. I'm still not clear exactly where this connection post is found.

Glad you were able to figure this out and dielectric grease is exactly what I'd use as well, especially with the protective zinc gone form the post. Also, a product called Deoxit D5 or S5 is excellent for protecting electronic connections.

Thanks for the info. How do you get to this bulkhead post?

I have edited the post to describe the location of the rusty nail

Thanks for the update, but so everyone doesn't have to go through that long post looking for the edit, here's the pertinent info:

Apex, I had the same issue on my 987CS and drove me nuts trying to find the cause, untill I started to wiggle the positive cable I was finally able to locate the issue. IMHO, the female side of the connector that looks like a closed coil spring (a Mickey Mouse design..) it connects into the male portion with pure friction..! My solution was the same as yours, cleaned the male post with emery cloth and cleaned the female portion with a tooth brush and carburetor cleaner, and assembled with dielectric grease to keep the corrosion away. Please note that your male connector was way worse than mine

"Please note that your male connector was way worse than mine " ...That's not what she said...

Hahaha 😂

What year car?

Dave, 987.1 (2006-2008) not sure if this applies to the 987.2 (2009-2012)

I've resisted posting this - since it always seems to start some controversy - but "dielectric" = non-conductive. Googles AI has this to say about it: The important point here is - you really want bare metal-to-metal contact for the best electrical connection. You don't want to apply an insulating layer like dielectric grease between the contact surfaces. As the AI points out, it's best used OUTSIDE the connection to keep water from penetrating the junction. Japanese cars used to use grease on all of their connectors, and I think that started the trend of slathering dielectric grease on connections. Thing is - the grease the Japanese manufacturers used was a lithium-based conductive grease. It was not a dielectric grease. Just sayin'... sometimes you make things worse that you thought were being made better. In the case of this connector - an odd design - if I was to use a grease in the interface, it would be a copper based anti-seize grease, which is conductive, and just apply a very thin layer to the post after cleaning it of any rust or old grease.

That's a very valid note! I didn't even think that through properly when I did it, I was just thinking about keeping moisture out. I'm going to make a note of inspecting it tonight and removing the dielectric grease, I'll have a look at the white lithium and anti-sieze grease I have already to see if either of them are conductive and apply that instead.

Good points . I'll be sure that the stuff I'm using is conductive, and that it keeps corrosion out of connectors. Thanks much,

Dielectric grease is a very misunderstood product. It is misapplied in many situations. It is recommended for applications such as the rubber boot on the coil pack, but not on the terminal of the spark plug . What is actually needed in these situations, and on the contact points of connectors and electrical terminals is ‘Electrical contact grease’. It establishes a good contact at the point of connection, while reducing arcing and oxidation. As a former electrician, we used it in service panels where the primary is landed in the panel lugs. A trade name is NOALOX, to reduce oxidation and maintain a good point of contact. Without it, over time and the effects of oxidation, resistance increases and the current draw goes up, leading to increased heating of the conductors. Reading up on it further, it is recommended to use it sparingly on the terminals, wiping off any excess which would lead to arcing and the unwanted conduction beyond the contact points of the connector. I use it sometimes on bulbs, putting a tiny amount on the tip, and wiping off the excess. Cotton swabs work well to apply it, even removing most of the cotton tip first and dabbing the tiniest amount on the contact area, them wiping it to leave just a sheen behind.