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cycle of death


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I've had the flat battery thing going on for a while with my 997 GT3. After hours of forum searching, plenty of frustration and money wasted I think I've narrowed it down and am looking for suggestions.

If after a drive I sit in the car for about 10 minutes and let it go to sleep, I can observe a weird cycle. First, I hear a very faint click of a relay from somewhere on the drivers side of the car. This is followed by the cdrom going through the initialization thing they do like when you first get in your car. This cycle of 1.) relay click followed by 2.) cdrom noise repeats forever on about a 30 second interval. If the car isn't on a battery tender, the battery will be flat after 4-5 days.

I thought it was perhaps a bad PCM so I pulled it out. Though it might be the PCM cdrom killing the battery, I now think that is more a symptom and not the root cause. With the PCM removed, I still hear the relay click every 30 or so seconds. What's extra bizarre is I've confirmed that this only happens when the main headlight switch is set to the 'off' (the dot) position. If I move the switch position to 'home', this weird cycle doesn't happen and the battery won't go dead.

Has anyone experienced something like this? Is there some extra circuit open when the light switch is in the off position?


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  • 2 months later...

I find the relay that's clicking, grab a wiring diagram and chase it in that fashion. Bad grounds could be the cause but not likely. Id suspect a bad relay or whatever controls the relay, or whatever input controls the relay.

And before I did any of that, I'd put an amp meter in series with the ground side of the batter and start pulling fuses. You should have .05 (50 milliamps) amp draw +/- a little bit after all modules have gone to sleep.

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