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Drained battery problem

Discussion in 'E46 (1999-2006)' started by beforr, Mar 8, 2009.

    beforr guest

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    I bought a 2002 330ci in November w/ 45K. Started without a hitch since I've had it. The only electrical problem I know of is that on two occasions, the left rear running light remained on after the car was completely shut down and light switch was off. Starting back up and shutting down fixed it.

    The other day I tried to start the car and the solenoid clicked rapidly, but no start. A quick check of the voltage showed 10 volts. I jump started it and ran around town for 40 min. When I turned it off I made sure the rear light was off. The next morning I tried to start it again and got the same result and same voltage. I'll check tomorrow if the battery charger is functioning properly.

    The only thing I can think of is a relay or switch that may be hanging and causing the battery to drain. Like I said, the rear light was off so I don't suspect that one for the moment. Is there a relay on E46's that is normally supposed to turn off all accessory circuits if a light remains on inadvertently (like my '98 Taurus)? Are there any glitches or problems of this type typical to the E46?

    Thanks much for your help.....Bob
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    mooseheadm5

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    The battery drain can be caused by almost anything, and will take some diagnostic work to find. Once very common thing, though, is the blower motor final stage, which can cause the blower fan to work while the car is off. This will definitely kill the battery overnight. You may even be able to sit in the car with the key out and listen (or feel) for the blower fan running. It may do it intermittently, so bring a good book. It will be normal to hear some noise out of the heater flaps for a minute, but the blower should not be on.

    beforr guest

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    Well I have heard an elec motor hum of some sort right after engine shutdown for a few seconds. Would that be the heater flaps perhaps? Don't think I've noticed any other noise from the engine at any other random time in the garage, tho. Like you said, I would probably have to bring a book.

    K. This will give me something a little more to discuss with the tech at the dealer. I appreciate the heads up. You aren't in the North Jersey area by any chance are you?

    Best, Bob
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    mooseheadm5

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    You'd have to sit in the car to catch the blower fan running. I am in VA, but there is absloutely no reason you cannot find a good independent BMW shop in the area.

    beforr guest

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    Well I think I found the culprit. This car will illuminate the turn signal light steady if your blinker is on when you shut down the engine. The light will stay on until your battery is dead with no warning beep to alert you when you open the driver side door. I think my wife inadvertently left this light on after signalling a turn into the driveway and then not noticing the turn signal was still on when in the garage.

    This is part of the pathway lighting system provided in this car and not a very useful one IMHO. It is a real trap since there is no warning for it other than the light being on. The dealer says this option cannot be turned off at the dealership, so I just gotta be careful.

    Thanks for all your help, guys!

    Best, Bob

    bmw22mel guest

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    My old 2002 did the same thing. The dealer told me it was due to European cars having to have street-side lighting when parked on street.

    Didn't believe him then, either. FWIW older cars had a relay that would shut off the headlights when the ignition was switched off.

    beforr guest

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    Yep. Even my 98 Taurus will save the day with a global relay that keeps the battery from being drained by something like this. Oh well. I'll just be careful. Thanks...Bob
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    mooseheadm5

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    Yeah, that is a feature of your car. Old Benz's can do this too.

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