week vacation = dead battery

Came back from Vaca and my E39 was dead again. 2nd time it's happened to me. Batt is new, alt works fine. It's only if the car sits for more than 3 days. What are the most likely culprits here? the AC sampling fan?

naahhh....not the ac sampling fan.that one shuts off after 16-17 mins. as does the orange P led at the shift selector lever.

you have an electrical leak somewhere.or maybe one of the lights are not shutting off when it shud.check: glove box light,trunk lights and cabin lights.

google to find elect leak trouble shooting/elimination process

Could be the FSU bringing on the aircon fan, that will kill a battery quicktime. It can come on when the car is asleep and the keys are out of the ignition. Next time the car sits for 3 days disconnect the battery at the start. If OK after 3 days that will at least tell you the battery is not the culprit

Fsu

Battery is new, and load tested perfect. I am 200% certain there is a drain. Watched some FSU vids on YouTube. I can't believe this box turns the blower motor on when the car is off. That's new. weird. And the next question .... how much $$.

Having been a victim of the FSU battery killer I continue to be puzzled as to why BMW engineers decided that the aircon fan system had to be live at all times. From this and other forums it is obvious that the FSU failure has and will affect all E39 owners some time. It would seem to be much more sensible to have that circuit only live at the accessory and above settings of the ignition switch. Cannot help you with the price info as we get hammered for such items in NZ, (cost me $300+ to have mine replaced), only advice is to insist on genuine OEM replacement.

Originally Posted by FLE39

And the next question .... how much $$.

$50 at autohausaz

Back when I bought mine, I had just joined Bimmerfest (found it looking for the FSU answer) and didn't know any better, so I bought it at the dealer for $120.

Originally Posted by FLE39

Battery is new, and load tested perfect. I am 200% certain there is a drain. Watched some FSU vids on YouTube. I can't believe this box turns the blower motor on when the car is off. That's new. weird. And the next question .... how much $$.

Typically $50 to $100, depending on the online source. As previously mentioned, Autohausaz has it for just under their $50 minimum for free shipping. So order an oil filter or something

https://www.autohausaz.com/search/pr...d=1370988@540I&year=2001&cid=24@AC %26 Heat - Climate Control&gid=6557@Blower Motor Resistor/Regulator

www.autohausaz.com is the website
64116923204 is the part number you want

BUT, before ordering, I would recommend confirming the problem. Just shut the car off, and sit patiently in the car, and after 10 or 15 minutes you should start hearing the heater fan motor in the dash cycling on and off. If not, then you may have a drain somewhere else. Instructions for replacement is on this forum, just do a search. The Behr part you get from autohausaz will be the upgraded part, so this should be the last time you ever replace it. (BMW revised the part several times between 1997 and 2003 or 2004, due to all the failures)

Originally Posted by kiwiland

Having been a victim of the FSU battery killer I continue to be puzzled as to why BMW engineers decided that the aircon fan system had to be live at all times. From this and other forums it is obvious that the FSU failure has and will affect all E39 owners some time. It would seem to be much more sensible to have that circuit only live at the accessory and above settings of the ignition switch. Cannot help you with the price info as we get hammered for such items in NZ, (cost me $300+ to have mine replaced), only advice is to insist on genuine OEM replacement.

Agreed, but once you replace it with the most recently revised part number (around 2003 or 2004 was the release date), there should be no further replacements. Mine was replaced at least a couple times during the factory warranty period, and failed a final time outside of warranty in 2005 or 2006, I bought a replacement at the dealer for around $110 and it has been fine ever since. (knocking wood... )

Thanks guys. Appreciate all the help. I'll do the easy test first. Sit in the car and play on my iphone and listen for the fan for about 20 minutes. If nothing I'll do the amp-meter off the battery and pull fuses until I find the circuit.