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2000 FORESTER
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26 Posts
Discussion Starter #1
I parked my wife's Forester (2000 5-speed w/155k miles) last October, when the transmission started grinding. I went out to start it two weeks later, and the battery was dead. I mean DEAD, like the interior light wasn't on at all, but I found nothing on, such as radio or interior lights. So I charged it, started it, ran it for a half hour, then left it over night. It was completely dead again the next morning. I did this a few times until recently, when I disconnected the positive battery cable after having let it run: it started, even after sitting for a week! I again disconnected the positive battery cable after pulling it into the garage 3 weeks ago (to replace the transmission), and when I reconnected it today, it started right up. HOWEVER, the idle is very low (and has been low when starting it after charging): so low, in fact, that it feels like it's about to stall...and sometimes does. Also, the dash lights seem dim. I realize this is a relatively small amount of information on which to base a diagnosis, but what's the first thing that comes to mind, regarding a cause? Thanks for your help.
 

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Premium Member
2008 XS 4EAT
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9,878 Posts
How old is the battery? Most likely it is just time for a replacement if it is the original or even a replacement.
Starting the car and letting it run or taking it for a drive does very little to charge the battery. The alternator will maintain the battery charge through regular driving. If the vehicle is not being driven then you will have to maintain the battery via a battery charger ( the lower the amp, the better for your battery it just takes longer).
Your car like every one else's, has a lot of equipment that has components that constantly use small amounts of the battery's charge to be at the ready or reserve power as some will call it.
The battery's charge was probably already low and sitting continues to draw power. You would be better off to disconnect the battery as you did. I think you will find that once you charge the battery your idle will return to normal, but some batteries have just lived beyond their normal lifespan and will need to be replaced. All you have done with running it is replace some of the charge on an already low battery.

Keep us informed as to how this turns out.
 

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2005 Impreza RS Wagon Auto
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3,683 Posts
Have your battery and alt tested for free at any parts store, easiest tell is a multimeter across the battery while running, if its ~14v the alternator is fine, if not start saving for an alternator AND a battery.
 

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2009 Forester 2.5x
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706 Posts
Have your battery and alt tested for free at any parts store, easiest tell is a multimeter across the battery, if its ~14v the alternator is fine, if not start saving for an alternator AND a battery.
Please do get the battery tested. A dying battery can fool you for a little while: hold the charge, hold the charge, lose the charge, repeat...in the end, if the battery's dying it could leave you stranded at the worst possible time. Don't ask me how I know!
Steve
09 2.5X AT
 

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377 Posts
Start w/ charged battery and everything off.

W/ battery negative post disconnected, install an ammeter (0-1A range would be good) between negative post and battery negative cable to measure current draw.

If you see over 200 ma (not sure about this draw), you may have an excessive load from something. I think typical draw for ECU, clock, etc is < 100ma.

If draw is excessive, start pulling fuses in fuse box and watching current draw on ammeter. When you pull the fuse from the affected circuit, draw will drop to acceptable level. Now you know what circuit to investigate, you can find the faulty component or wiring fault.

good luck
 

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2000 FORESTER
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26 Posts
Discussion Starter #7
Thank you, all! :icon_biggrin:

The battery and starter were new in July, and there had been no symptons of a draw before I parked it, which is why I strongly suspected a short (the clock doesn't work). Why a short would occur spontaneously, and in an out-of-service vehicle, I couldn't imagine, but I thought it would have to be significant to kill a battery that quickly.

I suppose the following could have happened: the day I parked it, I could have inadvertently turned on the parking lights during the day, making it that much less likely I would have noticed it, which would have killed the battery by the next morning (I assume), by which time there'd be nothing to notice.

I plan to try TexasForester's tests tomorrow: I'll let you know what I get.
 

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2000 FORESTER
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Discussion Starter #8
I tried TexasForester's procedure: when I hooked up the multimeter between the negative cable and negative post, the needle jumped into the negative range. I'm not sure what this indicates, but I'd assume it meant that there was electrical activity of some kind. Anyway, I'm letting it sit, just to see what happens. Also, the idle is back to normal.

Thanks again for your suggestions.
 

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2010 Forester(sold 11/12) Manual
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49 Posts
I tried TexasForester's procedure: when I hooked up the multimeter between the negative cable and negative post, the needle jumped into the negative range. I'm not sure what this indicates, but I'd assume it meant that there was electrical activity of some kind. Anyway, I'm letting it sit, just to see what happens. Also, the idle is back to normal.

Thanks again for your suggestions.
Was your multimeter set to its "ammeter" function? If so, then reversing its connections (or throwing a polarity switch on the meter) should enable you to get a reading in terms of current drain. I believe there should be "some"--but not close to a full amp.
 

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2000 FORESTER
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26 Posts
Discussion Starter #10 (Edited)
Think I've found the problem!

Yes: later, I was walking past the car, and it dawned on me: maybe the current has to run through the meter in a certain direction, in order for it to read properly. So I tried it again: the "-" lead on the meter should contact the "-" battery post, and the "+" lead should contact the "-" battery cable. The needle pegged above 150 mA immediately.

Anyway, it turns out that pulling fuse #30 in the engine bay fuse box would discontinue the drain: it's marked "Clock / Light" in the manual (and "Clock / Room" on the fuse box cover itself). So I disconnected the dome light, then the clock, but nothing changed. I pulled every fuse in the interior fuse box, too: pulling #9 (I think it was) dropped the draw to about 130 mA, but that still seemed excessive; pulling the other fuses had no effect at all.

So for no reason in particular, I decided to pull the stereo: there's a wiring harness adapter between the aftermarket stereo and the car's stereo wiring harness; I separated the adapter from the car's harness...and the heavy draw stopped! So I plugged the adapter back in to the car's stereo wiring harness, and disconnected the stereo from the adapter...and the draw was back. Huh? That's right: the problem was with the adapter! I had wired it so that the stereo would have constant power, so I cut the offending wire, and the heavy draw stopped. However, I don't understand why it would cause a draw at all, if the stereo's not on. And I really don't understand how it could cause a drain when the stereo's not even attached!

This is interesting, too: as I repeatedly contacted the "-" battery post with the meter's probe, I'd hear a relay. I added some wire to the meter set-up, so I could open and close the circuit from inside the car, and found that the relay is located somewhere under the front/left corner of the dash. What's interesting is that turning the parking lights on and off seems to activate the same relay. A short somewhere?

Anyway, I’ll try to remember to leave an update next week, as to the status of the problem. Thanks again for the help: great work!
 

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2000 FORESTER
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26 Posts
Discussion Starter #11
Miswired stereo!

Thanks for all your replies!

I eventually isolated the problem to the stereo: it turns out that I had miswired the stereo. I know: moronic, right? That's what happens when you go about things to hastily.
 
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