BMW Battery Drain from Cluster Fuse #50, how to do?

If anyone has an issue with severe increased battery drain causing the car to die over night, and find that fuse 50 from your instrument panel was taking up significant power while the car was shut off. Then removed it and the car works fine, but need a new cluster.


Then here some tips to share:

  1. Better tell what year of your car to that the professional technician can look up the wiring diagrams and see what’s on fuse 50. You should know that your car, whatever the year, has self-diagnostic capabilities for unauthorized power draw after shutdown. There will be information stored in the computers.


“Need another cluster”? What, when the shop says they have no idea what’s connected to a given fuse? BOVINE EXCREMENT!!

Find a shop that has ISTA (BMW’s own diag/programming system), or, at least, Autologic.

Now, as an example, I just pulled up a power distribution diagram for fuse 50 on an ’09 335i, from Mitchell OnDemand, a pro website. It shows F50 as feeding Wiper relays 1 and 2. Understand that I would not trust this info alone; I would hook the car to ISTA or Autologic, and see what the power monitoring system has to say. Without this info, you’re shooting in the dark….that’s why they put this diag system on this very complex car.

You need a better shop — one that doesn’t throw $~1500 parts at cars without knowing why.