well nuff said. how can i tell if its the fsu? is there some sort of test? any suggestions are welcome. thx.(drains over night after driving all day.)

The simple test would be to disconnect the FSU and see if the parasitic draw drops into the normal range (30-60ma).

The simple test would be to disconnect the FSU and see if the parasitic draw drops into the normal range (30-60ma).

i need to read up on the location of it and what not. how hard is it to take out? i havent even been running the ac seeing as how my thermostat is on its way out.

You should be able to hear the blower running after the car "times out". Raise the hood and lower the front windows. Take the key out of the ignition and walk away. After 16 minutes, come back, but do not do anything that would start electricity flowing. Don't disarm the alarm or open the door. Just lean into the engine compartment or the passenger compartment and listen for the blower. If it's running, the FSU is a problem.

But if you know the battery and alternator are good, it's probably a safe bet that replacing the FSU will fix the problem. The original FSU failure is very common.

You should be able to hear the blower running after the car "times out". Raise the hood and lower the front windows. Take the key out of the ignition and walk away. After 16 minutes, come back, but do not do anything that would start electricity flowing. Don't disarm the alarm or open the door. Just lean into the engine compartment or the passenger compartment and listen for the blower. If it's running, the FSU is a problem.

But if you know the battery and alternator are good, it's probably a safe bet that replacing the FSU will fix the problem. The original FSU failure is very common.

do you have any links that could help me. im busy outside right now with the car, and im checking periodically. thx.

Sorry, no links. There is a DIY for FSU replacement I can link if you need that.

can i drive with the ac off and the fsu disconnected?

I don't know for certain, but I don't see how it could harm anything.

I don't know for certain, but I don't see how it could harm anything.

i guess i'll just drive around tonight and remove it one night i don't to drive her. i want a for sure answer if i can drive without it.

i guess i'll just drive around tonight and remove it one night i don't to drive her. i want a for sure answer if i can drive without it.

If it were my car, I'd do it. But you're not driving my car. I don't know for sure, so I won't tell you it's alright.

BTW, there shouldn't be a problem with it while you're driving, assuming your battery is charged, It's the current draw for hours with no charging that drains the battery.

Here's the DIY. http://www.540i6.com/finalstagereplacement.html 10 minutes max to remove. 15 min to put back in.

how do you get the plug off the fsu? i tried for a long time with no luck.

Did you squeeze the tabs on the plug?

You can drive with out it, but it's better to have it in.

It's a PIA to get out.. the tabs on the side are tought on the hands... and the akward position doesnt help, but you just gotta keep at it. ;)

Did you squeeze the tabs on the plug?

ya i squeezed the tabs but the damn thing would just not budge.

I used needle nose pliers, and pulled hard. be careful.. plastic hurts.

I used needle nose pliers, and pulled hard. be careful.. plastic hurts.

the tabs are on the side of the plug right?

Yes, The two plastic tabs on the side are to unplug it. Be carful not to snap em, but you may scratch em a bit. Try to wiggle to out... Remmeber that the part the plastic plugs into is part of the FSU, dont be a tard like me and spend 20 minutes tryin to take that off... :P

Yes, The two plastic tabs on the side are to unplug it. Be carful not to snap em, but you may scratch em a bit. Try to wiggle to out...

ok thanx a lot.:buttrock

Good luck.. let us know when you get it out.

i just change mine two days ago, the way i remove the fsu is like this. i use a small flat head screw driver about 5" long to push the tab down then wedge it b/w the fsu and the tab, then slide the fsu out for note( don't disconnect the wire you need the wire to pull the fsu out, my hand could hardly fit in there).

I have a 97 528i and was having the battery draining problem. I replaced the original FSU, and did not have a problem for about two months; and then it started again. I had the battery and charging system checked, and they were fine. The battery is less than two years old. If I pull the fuse to the compartment fan overnight the car will start. If I don't the battery is dead. Is it possible the FSU failed again, or do I need to be looking at something else?