battery discharges after 2 days of sitting - BMW Forum

need too know · 09-23-2009, 06:02 PM

Seems like blower motor runs all the time?help

witeshark · 09-23-2009, 08:47 PM

More info? As a guess, a climate control relay may be stuck.

need too know · 09-23-2009, 09:16 PM

2002 540 i where is the relay located?pulled all fuses no change drawing 12 amps any help would help thanks

witeshark · 09-23-2009, 11:46 PM

Not knowing more, I suggest a look at diagrams on realoem.com

german-speed-demon · 09-23-2009, 11:52 PM

i know some BMWs have a fresh air fan that draws for a few minutes folloewing car being shut off, perhaps it is staying engaged?

Just my 0.02.

gemnilvr · 10-17-2009, 10:28 PM

it is your final stage unit!! the fan will keep running and draining your battery, ur car should go to sleep after 15 minutes but if u have a faulty fsu it will stay running and the red/orange light next to the shifter will stay on as well!! easy fix and a cheap fix!! u can buy them on ebay and replace urself! search the threads im sure it is listed!

kwcannon · 10-18-2009, 08:03 AM

Mine was caused by a bad resistor "pack" used for fan speed selection. The dealer pointed it out and I repleced it. 15-20 min job. The item is located behind a small triangular pop-off cover located on the center console in the passengers side footwell. pop the cover, unplug the resister, insert new one replace cover. Opening is a bit small. Good Luck

Dirty_Tool · 10-20-2009, 01:27 AM

www.540i6.com - Final Stage Unit Replacement

vrouserun · 10-22-2009, 05:37 PM

no doubt the FINAL STAGE RESISTOR is bad. i had the exact same problem. it's pretty common

MBurns · 10-23-2009, 11:58 AM

Exact same thing happened mine a few months ago and it was the FSU although some suppliers still refer to it as a rheostat even though it’s a solid state device. Anyway it was located in the right side footwell in the side of the centre consul. My car is a right hand drive so I’m not sure if a left hand drive is the other way around but I think it’s still in the same place. You will see a plug connected to it and the unit itself stuck into the side of the air duct, which provides cooling for the unit. The part has a number of spikes sticking out of it. If you call to a BMW dealer they will most likely tell you this is what’s wrong if you mention the battery running down like that. With regards the fuse. The fuse for this is none of the normally visible ones. It’s actually located behind the glovebox. As far as I remember there are two fuses and the relevant one to try pulling, if you want to be 100% sure. The fuse is a 40A. Again My glove box is on the left so yours is probably on the right as I think your other fuses are there too.