I have a 2002 BMW 540i and while cruising at 80mph, the engine just cut off and the battery light came on.Was able tocoast the car to the should lane,triedstarting the car, but no luck.Then battery died completely. What can possibly cause this to happen.
Sounds like an electrical connection has failed, possibly at one of the battery terminals.
Is it the original battery? If so, it may have reached the end of its life.
A failed alternator is another possibility, as is a loose or damaged electrical connection to the battery.
I have never changed the battery. The car is now around 75000 miles. I am getting an alternator Saturday, and maybe a new battery and keep you all posted on what the outcome is. Thanks
Are you throwing parts at the problem or do you really need a new alternator? Have you had the problem properly diagnosed?
yeap - all fuses have been checked and fine, battery fully charged up and it seems like now the alternator is the last leg. From all indications, it seems like the Fuel Pump has nothing to do with it. In addition to the alternator, I am thinking about replacing the battery too - 7 years old. But that’s where things are now with my do-it-yourself mechanic. Just super nervous going to a shop shop and then go for the ride. Yes probably fixed first time out, but major $$$$$. So if the alternator doesn’t do it, at least it can be seen as an investment.
I also strongly suspect that it is the alternator. And, for future reference, running the car for at least 7 years on the original battery may be what did the alternator in. Having to “work overtime” to keep that weak old battery charged certainly did not do that alternator any good, and it may well have cooked it.
Well, I will find out tomorrow with a new alternator and a new battery. If this doesn’t fix it, then I am taking it in to the right proper show and just wait for my verdict. Either way, crossing my fingers that the combination of these 2 things will solve the problem. But my guy seems to be good with this stuff. I called the pro bmw shop and they told me that the battery considering it being 7 years old is due for a change anyway. SO that might be what killed it especially with the AC running etc. Thanks again.
Instead of crossing your fingers and throwing a new battery and alternator at it, how about having them tested?
Regardless of the results, you still should get a battery (yours is OLD), and you likely will need an alternator, but you should never just throw parts at things and hope they work. Diagnosis saves lots of people from lots of wasted money.
Alternators are a item with a very low failure rate on BMW’s . I haven’t done 5 in 30 years.Now GM thats a completely different story.
Wait till you see what that water cooled alternator costs. I had to replace mine at about 90K. Glad I get a parts discount and can work on my own car. If you are planning on paying for someone to do this work (battery and alt) better bring a grand with you to pay for it.
This thread dates back to late August, almost 6 months ago. The OP is long gone.