DME control

[macyfilms]

There is a curious design flaw in Boxsters wherein if you have locked the car, then the battery goes totally dead, there is no (easy) way to unlock the hood to jumpstart the car because you can't unlock it manually via the intended method. Thus, one of the options is to feed power into the car another way. By connecting power to the cigarette lighter receptacle, you can power up the car again and thus unlock the hood/trunk.

the problem is that if you get the polarity wrong, it can cause damage. you can also cause problems by turning the ignition key while doing this. thus, i cleared the data on my control unit. sadly, i had been warned of this but made the mistake anyway.

if you are going to leave your car sitting a long time, put on a battery tender, or disconnect the battery, or just leave it unlocked. i'm sure i'm about the 1000th person to go thru this ordeal.

does that explain it?

[ddb]

I figured you were trying to get your hood open by getting enough power to your battery via the cigarette lighter. I haven't had a dead battery issue yet, but if and when I do I'm planning on using the same method.

What I still don't quite understand is how exactly you reversed the polarity. I have a small, self-contained battery jump-starter that has a set of traditional battery cables as well as a cigarette lighter plug that I planned on using someday if needed. I haven't really studied how to use it, but I assumed it was a plug 'n play procedure that even I couldn't screw up.

So once you hooked up to the cigarette lighter what exactly did you hook up to on the other end? Directly to another car battery?

Thanks for an explanation. I'm trying to be somewhat prepared when my battery fails. It is over 4 years old and it isn't unusual for my car sits for a week or two. Thus far no problems but I'm sure my luck will run out at some point.

[Lil bastard]

@ddb,

why not just go ahead and replace the battery?

4 yrs. old means that it's definitely on the far side of the hill service lifewise.

seems a $60-$100 battery beats $300 for DME reprogramming, or more if it needs replacing, especially if the day of reckoning is relatively close at hand.

[ddb]

LB,

I don't disagree that replacing the battery now would be the smart thing to do. Especially if the choice was as simple as paying around $100 for a new battery versus reprogramming or replacing the DME.

I however think that is a false choice. I guess there is always a chance something could go wrong when attempting to get the front trunk open via power through the cigarette lighter or one of the other methods that I've read about. This thread was the first time I've read about a DME problem occurring while attempting to get the trunk open so it piqued my interest. I've read multiple examples of successfully opening the front trunk with power through the cigarette lighter without causing any damage.

I have a portable battery charger with a cigarette lighter option as well as traditional jumper cables and I wouldn't be afraid to use it if needed to open the trunk. If I ever get around to removing the front bumper I will make the emergency cable more accessible.

Thus far my 4+ YO battery still is starting the car strong despite the car sitting for 1 - 2 weeks at a time. I realize it could start fine one day and be dead the next. But as this point, I'm hesitant to replace the battery until I see some evidence that it is about to go. I'm just trying to be prepared if I get caught.

Thanks,

ddb