Power drain from fuse 27 (or not)
 

Hi


Having a power drain issue i tried to find out what's the drainer, because no surprise it's quite a problem to have a dead battery after couple of days.

Unplugged the usual stuff: heater hedgehog, nav/radio units (fuses 74 75 in trunk), nothing.

Then found another topic here talking about few fuses to try (27 42 48).
And bingo, after removing 27 the voltage stopped dropping even after few hours. Did not have to go thru the annoyance of the ampmeter diagnosis.

The problem now is to find out what it really powers, because "20A Multifunction control module 1" is not really explicit..
All i can notice it turns off all interior lights, even tho it's not fuse 42 supposed to be the one for "interior lamps".

Does someone have a detailled electric diagram of what is connected to what fuse?


Or anyone already been throught that and know where it goes?


Thanks

F27 is one of the continuous (Terminal 30) supplies to General module (GM3).

Does the vehicle go to sleep mode after 16 mins?

I guess it does, shifter P light goes off at least. Any way to be sure it goes to sleep correctly?
Looks like this fuse is also for the xenon headlights.

Found about the gm3 that it also controls remote key lock and windows. They both still work when i disconnect fuse 27

The general module controls a lot of stuff. It has several small relays and switches on it. It’s known to go bad. Mine has a drain from F60. Once I get it back, I’ll troubleshoot it more.

Well, not sure how to explain that, but after removing the fuse and putting it back (maybe 2 times after all the testing) it seems my power drain issue solved... by itself :dunno:

Stuck relay on GMIII probably opened cutting off power. Keep an eye on it.

Yeah not so much of a miracle after all, still have some drain after using the car again.
Is there a way to diagnose more precisely what is causing it? Test the relays you mentioned?
Or just replace the gm3 and hope the new one will be ok (need to recode something or it's plug and play?)

You are at the same point as mine. My problem is F60. 200 mA draw.
The GMIII is a known problem. You can see the inside of one here.
https://www.bmwgm5.com/GM3_Info.htm

Mine was sent for repairs and refurbished. It didn't fix the problem on F11 or F60. F11 drain was fixed with an EWS bypass. The GMIII does require coding. I need to acquire software to clone mine. Or find someone to clone if for me. If a clone fixes, the GMIII went bad after repairs. A shop quoted $1200 for a new module and coding. Even with a clone, they couldn't guarantee the sleep problem or drain from F60 would be fixed. If I pull F60, draw drops to 11 mA.

How many amps are going through the battery cable if F27 is pulled? With F27 inserted?

Haven't really measured the amps at the battery cables yet. Just left a voltmeter plugged in the cig lighter and checked every few hours.
Looks like a really annoying and costly problem to tackle..

F27 is a power source for GMIII. Assume something is else being supplied power or shorted out. Or the GMIII itself can be causing the problem. Determine how many amps are being drawn. How long does it take to drain the battery? I'm at a point, I can put a cut off switch for F60. Either an ignition power relay or toggle switch. When parking overnight, need to lock/unlock rear doors, or open the rear hatch and tailgate, F60 can be powered up. A seamless relay with key on power to power F60 seems ideal. No hassle other than wiring it in place.

Keep posting information. Maybe someone can help out.