Something is draining my battery overnight...
 

Every morning it's completely dead. When I leave for for lunch it starts fine, leave work for the day it starts fine, leave the gym it starts fine. By morning it's dead as a door nail. How do I diagnose this? Car is equipped with MSII, I've already disconnected the amp so that isn't it. I really haven't added any other electronics.


BTW, my batter is only 6 months old and MS says my alternator is doing just fine.
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How are you starting it when it's dead? The same thing was happening with mine, it would mysteriously COMPLETELY die, turned out the battery terminal clamp was cracked and would sometimes not be connected then i'd jump it which would make the terminal touch. Fixed it with a new terminal and voila. Probably a long shot, but its worth checking.

I have to use jumper cables and my truck.
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With a multimeter capable of reading DC current. Pull a fuse and stick the probes into the hole to complete the circuit. When you find the one that's got dark current on it, you know where to look.

I was with you until you got to "dark current" And Google isn't helping me with that.
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Current passing through a circuit when it ought to be "dark" (off.)

The radio will draw a milliamp or three to keep the memory alive, ditto the ECU. So will an alarm if you have one. That should be about it.


You can stick the meter inline with the battery itself for starters, just to make sure that this is in fact the problem, and you're not simply dealing with a battery full of koala piss instead of electrolyte, or something similarly annoying.

Cool, first stop tomorrow will be to buy a meter.

Thanks Joe.



I don't know if this means anything but I was poking at the fuses under the dash with a light tester and the defroster fuse had current going through it with the key off. Is this normal?
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no

Shouldn't be.

http://img37.imagefra.me/i5c1/thradd..._73a_u77ts.gif

The relay's coil is supplied by the IG2 position of the keyswitch, and thus, that relay should be open when the key is off.

Try leaving that fuse out tonight and see if the car starts in the morning.

Will do, thank you sir.
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Joe with the ninja edit.

I was thinking kind of what Joe said. In a similar situation, I stuck an ammeter in series with a battery cable and started pulling fuses to find where my problem was.

What's the word turd?

according to the '99 manual the defog fuse is hot at all times. however if there's power going through the rear window defroster relay, that could cause issue. check for voltage on the blk/red wire coming out of that.

but, like you said joe, the relay should be off. IF there was voltage through the a/c fuse AND defog fuse, then that would clearly be an issue.

He wasnt having issue until he made a fix on his harness, where I screwed up his a/c activation. I went through the diagrams to figure if that could be the cause but I see no way that wiring would cause any relay to stay activated when teh car was off. And it would be easy for him to see the clutch spinning or a/c fan running.

So Uhh yea, I left the defroster fuse out and she started rigt up.
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Phil told me last night that his car is wired for defrost but he doesn't actually have anything in his car with a defrosting element. Would that entail a bad switch? Looking at the diagram Joe posted it looks like that and the condenser are the only things that can bypass the heating element to ground. Not sure how the condenser plays into that mix.

hmmm.

Maybe your rear defroster switch is broken and not auto shutting off? It looks like to send power through the relay would require the switch to simply ground the relay...if the switch was stuck on, the defroster relay would be always open.

EDIT: yeah if that's the case, whatever the condenser is is drawing power.


Easiest check would be to put the fuse back in and check for power at the condenser (appears to be behind the driver seat near the floor).

Probably a stuck relay, then.

'Condenser' is just an older term for 'capacitor'. From the sound of things, and looking at the schematic above, I'd say the cap is shorted.
If your car doesn't have a defrost element, just pull the defrost relay and be done with it. It's probably 'stuck' anyway.

Phil said he heard a click when he pulled the fuse. I have a feeling the relay was stuck closed and removing the constant power source from it finally opened it.

He confirmed this morning that there was no power at his defroster connector with the fuse put back in.