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Hello all you fellow BMW owners out there!!!

I am new to this forum and so I am not sure whether im doing this right!!! I am Mark and I own a BMW 525iSE (2000) and I have a problem to solve !!!

I have had my car looked at by several people and on the face of it appears to be problem free. I have always looked after my car and of late it has developed a rather nasty power drain. I have had the battery replaced, and Halfords did a check on the battery and its fine, they also checked the alternator, its fine too. I took it to the entertainments place that fitted everything in it....and they found that the battery was fine and the alternator is charging at 14.85 volts and so thats fine too.

I was advised to buy a voltmeter and check the battery voltage every time she wont start as I understand a 0.5volt drop will make the engine management system kick in and say "NO im not starting" and so you just get a click click click, instead of trying to turn it over!

One one occassion it read 11.58 volts so should have started but never, on another it was 8.6 volts so wouldent start. We thought a sticky starter motor maybe but we are not sure.

I opened the boot today and checked the voltage again before starting her and it was 10.35 volts. So i knew it wouldent start and she never! as soon as I put the key in the ignition and turned to the first position, the battery voltage dropped at the rate of knots starting at 10.35...34...33....32...31.....30...29 ect one every second. took the key out of the ignition...it stopped.

Now to add to the problem, once she is started she will be ok all day and sometimes for several days before this happens again!!! It is really bugging me now and I am trying to think what to try next or how to eliminate faults.

Anyone who can help me on this problem I would really really appreciate it as its bugging me. I have a insulin dependant diabetic little boy aged 2 and in am emergancy I need reliability from my BMW!!! Please help me peeps! Kindest regards Mark :dunno:
 

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I have the same drain problem on my 2000 528iT and I've finally been able to isolate the problem to the Nav/Sound systems by removing the fuses that control those systems and finding my battery has remained solid. You don't mention what options you have on your car so I don't know if that's useful to you.

My next step is to reinstall the fuses while I first disconnect the Nav disc player in the rear to see if that helps; then disconnect the DSP amp if it doesn't help. I'm getting closer though no final "solution" yet.
 

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I had a short in the Aux Fan...The shorted fan caused a power drain like you describe. Once the fan was replaced, all was well. Hopefully it is as simple as that....A BMW dealer can diagnose that very easily.
 

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I would agree that the first place to look is the FSU causing the power drain; has come up here numerous times and is a simple fix. My power drain, which would occur whenever the car sat for about 3 days or more, was due to the glove box light staying lit due to improper closure and the button just not being pushed all the way when the box is closed; only noticed when I parked in my garage with the lights out and saw a very faint glow from the car. I put one of those sticky felt non-slip pads where the button should hit and turn off the glove box light, and problem solved.
 
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