what would make my battery light blink randomly?

Asked by Oct 25, 2013 at 08:08 PM about the 2005 BMW X5 3.0i AWD

Question type: Maintenance & Repair

Two days ago the battery light in my 05 BMW X5 started flashing like it had a loose
connection. The next day came on solid and after about five miles dash said'engine fail
safe mode" and shut down. Coasted off the road and tried restarting, key did nothing in
the start position. had it towed home thinking it was just an altenator. Before replacing
it, i tried starting it several times and the engine only turned over twice out of many
attempts.Tried taking off the negative battery cable over night and charged the battery
at the same time. today tried starting it again and only the miles outside temp and
"key in the ignition lock" displayed. No gauges or lights lit up like they normally would.
Checked the fuses, none blown, but did find a few "engine control" fuses to only have
2.5 volts. Didnt seem right to me but im not sure what they are acutally supposed to
be. Tried scanning it but scanner would not link up. What can i look for to possibly
solve this problem on my own?

10 Answers


We own an X5 for a short time due to the number of electrical issues. I would tell you to have a BMW professional look at it before you randomly try to fix it and cause further (read more expensive) damage by accident.

3 of 3 people found this helpful.

If the battery is week, you will get some weird electrical issues such as what you are experiencing. How old is the battery? I know you put it on a charger, what is the voltage? If it is over 5 years old, get a new one. See if the issues go away.

1 of 1 people found this helpful.


2 of 2 people found this helpful.

But a blinking light is always indicative of a failing alternator. Put a voltmeter across the battery terminals and check, with the engine running, for around 13.85 volts. If it drops below 13V you most likely need an alternator.

I cant even get it to turn over. key in the on position doesnt even act correctly.


A battery light always links to a bad alternator. You will have to be sure the battery is in good condition first even if you need to test it outside the vehicle. But this doesn't mean the problem is solved, when a bad alternator is found the battery gets damaged or viceversa


BMW vehicles are very high tech and use a lot of electronics so voltage is very important


bring the Car to an authorised BMW Dealer.. Otherwise, you could be looking at big repair bills from compounded electrical failures

It may be a bad crank shaft sensor?... aftermarket one?

It may be a bad crank shaft sensor?... aftermarket one?

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