turn on key - complete power loss

I drive a 2000 528i. this has happened twice now in the last week. I get in, turn key to start car, everything lights up as it should for about half of a second then everything turns off, complete power failure. I disconnected the negative battery terminal, let it sit for a few minutes, reconnect the battery and retry the start and everything lights up and the car runs normally. My TRIP has reset, the radio has reset, so there was a complete loss of power to the entire car, but whatever it is is resetting itself possibly because i disconnected the battery, but maybe it is resetting regardless of my battery manual disconnect.

thoughts??

1. Age of battery?
2. What is battery's voltage? Above or below 11.89 volts?
3. Does the battery have removable caps (or screw in caps) that allow you to check fluid around cells?
4. If yes to question above, have you checked battery fluid level?
5. If low fill with DISTILLED water only.

In addition to what QSilver7 said, I'd suggest you drive to Autozone or O'Reillys (or whatever you have where you live) and have them check the charging system.

I went to both, just in case, just this week for this thread:
> Detailed step by step diagnostic DIY ... dead battery ... parasitic current drain

Their test takes only about five minutes, in toto ... so it's easier than doing it yourself.

However, to do it yourself, as QSilver7 noted, you'll need to measure stuff:
- DIY how to test a BMW E39 battery & alternator

You might want to try the passenger visor test. That would indicate a faulty ignition switch.

Originally Posted by Fudman

You might want to try the passenger visor test. That would indicate a faulty ignition switch.

not familiar with the Passenger visor test, however this is a COMPLETE power failure in the car, would a faulty ignition switch kill power to everything? radio, odometer computer (mpg display, average speed display, etc.), etc?

Don't know but if turning the key is the trigger to the malfunction, I would start looking there first.

Fudman, what is the passenger visor test?

Originally Posted by thisbigguy

Fudman, what is the passenger visor test?

I typed /ignition switch F3 into the bestlinks, and I'm sure the answer is just a click away for you now ...

- Signs of a failing ignition switch (1) (2) or ring antenna (1) & the BMW TIS for when the ignition switch spins but does not engage (1) & rebuilding a failed ignition switch (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Besides all the above suggestion which are all valid, you might try cleaning your battery posts and terminals. Corroded connections will interrupt power.

you have a short with you positive battery cable. that issue hunted five times before i found the solution. but next time that happens get access to you battery and tap/shake the positive cable and it will come back on.

Had the same issue on my 528i - It was the battery posts. Even if they look clean, take them off, clean them very well, and reconnected very very securely.

Originally Posted by thisbigguy

Fudman, what is the passenger visor test?

It's #1 link from BB: http://bimmerfest.com/forums/showpos...26&postcount=1

+1 on the battery tightness check, this is a common problem.

fantastic feedback,thank you. looks like i have several things to look at/test this weekend. I will post follow up

I had a similar issue. Check your battery terminals.

OK. time for follow up: took the car to O'Reilly (Checker) and had the battery and charging system tested. both Passed with flying colors. I pulled the cables off the terminals and cleaned them with a wire brush, they looked very clean, but did it anyway. Battery is 3 years old. No view ports to check fluid levels, but it passed a load and charging test so that is not it. Several employees of O'reilly had the same idea that it is a short in the Positive battery cable, or in a breaker or a fuse right after it leaves the battery. There is a ton of stuff right there so I am not sure i will be able to isolate exactly where the problem is... may have to resort to a mechanic/dealer electronics systems test.