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Battery going flat after a couple of days standing

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So my new (to me) 986 battery goes flat after a few days with no use. I should have figured something like that when the previous owner stated he had just put a new battery in the car. Receipt was in the paperwork so I figure the battery is fine.

Having read through various posts on this and other forums, I hooded up a multimeter in series with the battery and started pulling fuses one by one. With all the fuses in I'm seeing approx. 500mA. That'll kill a battery in a few days.

After working my way though all the fuses I have identified the culprit is D9. With that out I see about 150mA dropping to about 30mA after an hour or so.

Now D9 is listed as the Audio Option pack and sure enough with the fuse out I lose the amp. The car has an after market CD player which still works with the fuse out so that's wired somewhere else. I just lose the amp. Now all of this is without the key in the ignition.

Again after some more reading I suspected the ignition switch as I would assume the audio pack would be turned on with the key in position 1. So I have changed the ignition switch but no effect.

So now I'm a little stumped. What to do next. For now I've pulled the fuse which will at least keep my battery good.

I wonder if someone in the cars history has done some funky wiring on the amp but it all looks stock.

Any ideas or suggestions where to look next would be greatly appreciated.



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No the 500mA is as soon as I hook up the battery through the meter. It drops to about 350mA after an hour or so. The draw on D9 looks to be about 300mA. So 500mA as I hook up the battery. Pull D9 draw drops to 200mA.

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The fuse D9 powers the amplifier ONLY and it's always hot (so it's not controlled by the ignition switch). Check out the diagrams here for a 996 and yours should be similar or maybe even identical. In the upper right of the amp in the diagram, you see a "Term 30 +" pin, which gets power from fuse D9.




There are two connectors on the amp. Maybe you can further narrow down the drain by unplugging the connector to the speakers (the bigger one) and see if that changes anything (in case current is leaking into one of the speakers). Then reconnect it and unplug the smaller one (that connects to the radio) and see if that changes anything. Or there's an internal leak inside the amp.

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Are you positive that the amp is supposed to be on all the time?  I installed an aftermarket 2 DIN system in my 2000 Boxster, and if I recall correctly there was a wire that was "hot" all the time so that the radio could retain all the presets.  There was another wire that turned on the amp and the antenna but only when the head unit sent it a signal to switch on..


Is it possible that the person who installed the aftermarket head unit hooked up the amp so that it was turned on all the time?


You can find wiring instructions here:




(Scroll down to the second post in the thread.)  You can compare this to the wiring that is in your car.


Good luck.

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No, I didn't mean the amp should be hot all the time. I mean fuse D9 is hot all the time and it is connected to the amp. There could be other control signals from the radio like you said that turn on/off the amp.

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I read your post more closely and I see that I misunderstood you.  I still think that the original poster should look at his head unit wiring to determine whether it was done correctly.


When dealing with the work of previous owners, you should never rule out the possibility that someone made a mistake.

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  • 2 weeks later...

A quick update. Traced the amp control wire and it was indeed wired to the +batt on the stereo. There is no amp control output on the stereo so I have now wired it to the +ignition. All good and battery not draining now.

Many thanks for the help


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