Battery drains in two days through fuse 31
I have a little mystery to figure out. I have my battery drained by a component connecting via fuse 31, namely: clock anti theft, immobilizer, instrument cluster power, buzzer, board computer, they are all on there. The draw is 0.25 amp for 60 seconds, then drops to 0.05 amp , which would be nice if it would remain there, but alas, it comes back to 0.5 amps after 60 seconds precisely. One local tech told me about the BMW board computer having a dedicated small watch battery which died and caused a similar effect in another BMW. It sound very plausible to me, given the regular nature of the intervals, one could nearly rule out a stuck relay or short.....or am I mistaken? So did anyone ever dig out the computer and find such a little battery which can be replaced? Or did anyone ever have a similar pattern and found the solution? Another weird thing is, that when I pulled the fuse, the car started up as if nothing was missing, except for the cluster no longer indicating its stuff. What gives here?