Hey guys, I just had my first electrical 'issue' come up with my 100% stock 2004 545i and was hoping for a little help.

I am away from home due to work for weeks on end and the car remains parked at home. A few weeks ago I had a dead battery and after charging it, all I could achieve was an 11.8v charge and the following day it was dead again. It also was in 'Limp Mode' with several lights on the dash including active steering, cruise control, and something about the windows. At this point I decided to replace the battery and the Limp Mode and all error lamps went away EXCEPT the active steering and the car started and ran fine. Next day.... low battery preventing engine start.

We did have alot of rain that night and there was some condensation in and around the battery and fuse panel. I dried everything out real well and charged the battery, but the problem remains. I removed the MPM to inspect the guts and did find some corrosion but its otherwise not too bad. I also noticed the car will NOT go into sleep mode via the amber light at the shifter location. At this point I decided to disconnect the IBS and remove 5 fuses at a time waiting 20 min looking for sleep mode in efforts to narrow down to the one or more systems preventing sleep mode and found NONE that would.

At this point I am pretty stumped.... I did however notice when i connect the negative batt cable to the terminal I hear the black relay in the trunk fuse panel click on or 'engage". So I did a parasitic draw test with and without that black relay installed. I found the draw is present out past a half hr with an 8 amp draw, and almost no draw at all with it removed after 15 min! I did notice the amber shift light goes out the instant the black relay is removed, so I am unable to confirm sleep mode with the relayremoved.

Main question... What all components of the vehicle draw through that relay, and is it supposed to be powered 'engaged' for 30min or longer after connecting the battery?

Any help would be greatly appreciated!

 

Confirmed....

I left that relay out over night and the car started 100% and the battery lost no charge what so ever.

Anyone know what all triggers that relay? Im guessing charging system because with it removed I cannot turn over the engine. Possible alternators voltage regulator can parasitic draw with key removed and closed up?

 

Ok, with the relay plugged in and everything connected EXCEPT the IBS, the amber light next to the shifter goes out after 1 hour... Does this seem right? I have read dozens upon dozens of threads stating the light (sleep mode) should happen at 16 min. :^/