Battery Flat

[zaphodb]

I have a BMW X5 4.4 2000. Over night, the battery is going flat. Sometimes a fan keeps running somewhere under the hood (I can hear it best at the grills by the windshield). It does not run at a constant speed, it modulates erratically. So I suspect this is the problem. I also have a problem with the climate control where it modulates for no reason (from full fan to off). Could be related? Any ideas? Could it be a sensor or something??

[nukeduster]

bust out with the multimeter. bad fan relay most likely. after that, bad computer somewhere. scantool would be most helpful in a car that new, after doing a power drain test circuit after circuit.

[97alpineM3]

^^^ Thus... that'd be a dealer issue... unless you are highly electronically inclined..

Good Luck,

Les

[Bear]

The fan MAY be the fcooling fan from EML ( I have a '88 750 and that is a common sound on this car). Disconnect negative battery cable and hook amp meter between negative cable and battery negative post and you should see about 50ma, if not, start pulling and replacing fuses until the urrent draw falls to around 50ma and you have your culprit.

[edkal]

i had the same problem with my e39. i changed my fan resistor, problem solved..