I have a 1997 328i and for about a year now we've been having issues with the car dying and having to jump it. It seems to be getting worse the past 2 months especially this morning even by jumping it, it wouldn't start. This problem mainly happens when the car is not driven for a day or two. The battery is fairly new. Is this an electrical problem or is something draining the battery??? Mia G. (by the way we are the original owners of this car)
From the description, it sounds like you have an electrical device draining your battery. Common items for this, are the lightbulb in the trunk is still illuminated when the trunk lid is clsoed, or the bulb in the glove box is still lit when the glove box is shut. Removing these bulbs temporarily, and finding out if the problem still occurs or not, is the easiest way to diagnose those particular components. I would also suggest that you inspect the wiring harnass that comes out of the trunk lid (drivers side) and enters the trunk. This wiring loom is notorious for creating shorts, you need to slide the protecetive sleeve down, and inspect the wires inside to see if any insulation has worn away, creating a short between wires.
Other issues that I have seen cause a key off battery drain are aftermarket stereo installations and various modules not going to sleep. Do you know how to use a digital multimeter?
update thanks for the replies! I haven't found the problem. but I'm pretty sure it's the trunk light.(I have to let it sit this weekend untouched to see) it's not the radio which is good and I got the battery tested and it's not that either. btw how would I fix the light in the trunk? about a year ago the car was rear ended and was fixed by a shop that did an ok job but lied to us. could this be from the repair?
