02 540i - battery or alternator??

[Bimmerrules]

Yesterday coming back from the bay area I noticed the battery light on the dash going on and off and later it stayed on. The car was driving fine and I made several stops turning the car on and off without a problem but the light would not go off. I went to work and stopped the car for about 4 hours. Once I got back in the car to my surprise it turned on without a problem but the battery light remained on. I ran some errands and no problems, turned the car on and off just fine. On my way back home, about a block from my house a bunch of lights went on in the dash and after that I felt as if the transmission jumped and a warning popped up in the dash reading "trans fail safe". At that point it felt as if it was on 3rd gear only. I made it home and turned the car off and tried to turned on right after and it would not fire. The weird part is that the alarm and door locks works fine. Just now I went out to try and turn the car on again and I unlocked the car with the remote key just fine but the car will not fire up. Help please!!
Does anyone have an idea as to why this is happening?
Thanks in advance!

[darkhorse737]

1) check all fuses first.

2) have battery checked to see that it is accepting a charge and there are no dead cells;

3) if 1 & 2 are good, then alternator failed.

* in most cases it is #3.

and yes, car will not start when voltage drops below the 10.5 volt level. injectors fuel pump and a host of other electrics are disabled

[Bimmerrules]

Thanks for the reply! I will try your suggestions and post the results.

[Dirty_Tool]

Originally Posted by darkhorse737

1) check all fuses first.

2) have battery checked to see that it is accepting a charge and there are no dead cells;

3) if 1 & 2 are good, then alternator failed.

* in most cases it is #3.

and yes, car will not start when voltage drops below the 10.5 volt level. injectors fuel pump and a host of other electrics are disabled

agreed

[Bimmerrules]

Thank you guys very much!!! It was the alternator. Got one at autopartswarehouse.com for a decent price. Thanks for the help!!!