Getting to bottom of Battery drain...

Seros · #1 04-27-2009, 05:41 AM

MY beloved X5 has been a real pain in the behind since i bought it 6 months ago. FYI, It's an 2002 4.4 X5.

SO far we've replaced a faulty FSU and a faulty radio u nit which was causing a current draw. The problem is I'm still having dead battery issues even with these parts replaced.

What makes this even more difficult is that every time I take the car to my auto electrician there is no abnormal current draw on the battery..... never.

So my problem is intermittent and can happen over a period of 8 hours (while I am at work).

Two thoughts... Sat Nav / TV? Or keyless entry? Those were the 2 things I used last night before it died again (for the 10th time). Also battery is supposed to be ok as is the alternator. My auto elec has been over it with a fine tooth comb.

And yes it does go into sleep mode, but maybe not all the time?

Any thoughts would be really helpful.

Thanks,

L.

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Essam Khafagi · #2 04-27-2009, 07:05 AM

I'd suggest taking her to the dealer or someone with GT1 to check the error codes

toddjoh · #3 02-12-2010, 09:01 PM

I'm having the same problem.
Replaced the battery and alternator. Dead batt next day. recharge, next day dead again.
Took it to OReileys and had both tested found no problems. Disconnected the battery for a few mins and then re-attached it and the car drove all week no more problems. Today the wife calls car is dead at work. after sitting only 4 hours. Any clue what to look for?

Seros · #4 02-13-2010, 01:26 AM

ok, i know what a pain in the ass this can be as i recently had the same issue.

First thing. Recharge the battery and re connect it. What you will need to do is see if the car is switching into sleep mode.

How you do this is by checking the little light on the gear shifter, it should turn off after 15 mins. What you'll find is it will PROBABLY turn off, but then randomly switch on after a couple of hours. You'll need to just keep walking back to the car and checking through the window, but DO NOT touch the handle or open the locks etc.

Now if it is doing this, my solution was really fucking simple... well it was after I spent a fortune on trying to find a solution. Turned out, that not even BMW knew what it was. Sad but true.

What I did was remove the fuses 1 by 1, until the car stopped jumping out of 'sleep mode'. Luckily it only too 2 fuses....... it was #73 which was causing the problem.

So i removed it, and everything was still working perfectly.... so i never bothered replacing it or going back to BMW. Sounds strange, but it's true.

I suggest you try that.

Cheers,

Luc

p.s. The other thing which is may be is the internal fan which sometimes is faulty and doesnt switch off. But im sure they've check it as its a common issue.

toddjoh · #5 02-13-2010, 10:43 PM

I've recharged the battery, and removed fuse #73. Now we will just have to wait and see if it is now resolved. Fingers crossed.

toddjoh · #6 02-15-2010, 11:01 AM

Fuse #73 also covers the Stereo and Nav system. Wife was not happy. Maybe 73 on your car is different. #74 is labeled phone and nothing else on the chart. So I've reinstalled 73 and removed 74.

our car is 2002 4.4i X5
BTW does anyone have a better chart of fuse functions than the rather poor label on the door. Nothing in the owners manual that I've found.

recklessspyder · #7 02-15-2010, 11:46 AM

I pulled #73 on my 2005 because of the faulty TCU. My key to knowing something was wrong was that the red light for the phone stayed on all the time after a battery drain and reset.

Thank the forums for giving me the answer after a week of struggles and trickle charges.

toddjoh · #8 02-15-2010, 12:05 PM

Reckless, does 73 take out the stereo on your X5? It does on mine, but 74 seems to only take out the phone which we do not have anyway. I have not done any draw test yet. My son has a multi meter that I will need to borrow. Waiting on warmer weather also.

recklessspyder · #9 02-15-2010, 12:13 PM

nope, I think it's isolated to the bluetooth (tcu) module....but now you're making me want to check if it's actually 73 or 74.

Point being...no TCU, no battery drain.

If it's the TCU, some people have gotten a free replacement since it would interfere with BMW assist. I haven't taken mine in to see what they will say yet. If they won't exchange it, i'll eventually do it myself.

toddjoh · #10 02-21-2010, 11:38 AM

After a week no problems with fuse 74 removed, the wife called Friday and the car was dead at work again. It was parked for only 4 hours before going dead. She said that when she turned off everything she was still hearing a fan sound. Not sure where it was coming from. I've read about FSR on several threads. Would the Final Stage Resistor AKA, Blower Motor Resistor, AKA Hedgehog, cause the fan to continue running and thus drain the battery. I've not noticed any other issues with the climate control other than the temp seems to make little difference in comfort. But that is I think a different issue. Anyone know of how I might test the FSR?

It appears to be an intermittent problem so it's going to be hard to pin point.

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