928wolf

Looking for some ideas. I just got some new tires put on my car, stopped into the grocery store, came out and the car was dead as a doornail. Put the key in the ignition and nothing, no dash lights, no clicks, no response at all.

Here's a couple of interesting details and a sort of sequence of events:

Clock and interior lights were still working, but as I opened the driver door wider the clock faded out, and faded back in as I closed it, but never went off. This tells me that uninterrupted power was connected, but anything requiring the key wouldn't work. But why would the door have anything to do with it???

I opened the rear hatch before I got in the car to put groceries in, then closed it. Car wouldn't start.

I got in to the battery compartment, fiddled around with the battery connections, and it started right up. No ill effects that I can see, drove home just fine, went back out a few hours later and tried it again, no problem.

As a side note, I had taken the battery out to get tested the weekend before, but it tested fine. I thought I had secured the connections a lot tighter than I had found them. Ground strap in the tool compartment? I loosened and tightened it as part of my "fiddling" with the battery. But power was still going to clock, so I kind of discounted that.

My car has a (factory?) alarm system, it seems to be sensitive to how and in what sequence you open the hatch and doors. Would the alarm system shut down the ignition???? Just a thought, have no idea if it's relevant.

The tire place just put the car up on a standard automotive lift, I can't imagine that they did any damage, but who knows?

I am planning on taking the car to the NC mountains this weekend, but something this random has me nervous about getting stuck 100 miles from home.

Any ideas? Thanks in advance for any help

Leon Speed

Could be the alarm system, it can be armed and disarmed with the long key in the hatch lock.

The Patman

I'd certainly look at the battery connections real close again. Especially the ground termination point in the tool area as you mentioned. Further, I'd check not only the clamps but the axillary nuts that hold extra connections to the clamps. Also, I've heard that the ground cable (flat braided) can become almost unusable INSIDE the exterior coating from internal corrosion. I've seen this type of instant "no start" thing before, it's almost always a battery or power issue. Sure could always be something else, but you're describing a power issue right now. Oh, and yes the alarm "can" keep if from starting, but it doesn't sound like what you are describing. And I'm not sure how the door opening aperture could affect this. Yes, there are wires in there including alarm wires, but dimming the clock seems like low power or a short sapping power...which is a whole 'nuther issue! anyway, safe to start with a good check of the ground cable and all connections to battery. can move farther later. Oh wait. put a meter on the battery at rest without engine running and then after a start and look for around 12.7 volts unstarted and around 13.5-14.25 after it's running...at the battery POST not clamp.

Tom in Austin

I have a good extra battery ground strap if you want to try a different one, just PM ...

Mrmerlin

What Patman said , well written!

928wolf

Interesting, the last time I opened the hatch I used the red key (for some strange reason). It sounds like I set the alarm by accident maybe? Obviously I need to read up on how the system works. I've treated it as an annoyance up until now.

Landseer

Ground strap. Unstable and variable voltage, can go absolutely dead on you in blink of eye.

928wolf

Couldn't reproduce the problem from the alarm standpoint, so I've ruled that out.

I thoroughly cleaned the contacts on the battery strap and frame connection. Tried to reproduce the problem with no luck. Plan on playing with it some more.

Thanks for the help!

Randy V

Could be a faulty ignition switch.

Next time this happens try jiggling the key in the switch.

928wolf

Had the problem again, this time 100 miles from home. I jiggled the battery ground strap and power came back. It looks like you guys were spot on, getting a new battery strap.

Thanks again!

MainePorsche

Looks can be deceiving.
Cut ground strap insulation off to confirm.
Also, is your battery adequately vented ? Acidic vapors will cause degradation especially down in the bin.

fossberry

It certainly wouldn't hurt to replace the battery ground strap as preventative maintenance regardless. The one in my wife's 968 seemed fine but was responsible for it not starting. A resistance test really only needs 1 strand connected to give zero ohms. You really have to load the cable with current to test and if you can crank the car, well that's the biggest load on the battery and associated ground.

Although mine didn't die completely it would randomly shut down to 4 cylinders. If yours is fitted with the protection system (mine is a '91) there is a test you can do to see if there's a voltage mismatch between the cylinder temp sensors. In the end I purchased the bypass relay rather than fork out hundreds for a new temp sensor. If I remember rightly it was a system they eventually ditched anyway.