Available from the German E34 Forum.
http://www.e34.de
When you are at their page click on the left side the followings : Schrauberecke>Tips und Tricks then go to Elektrisches.
The index is of course in German language, but that should be no problem for you clever guys. Diagrams are in English language.
They have:

Schaltplan Motronik 1.3
Schaltplan Motronik 3.1
Schlatplan LE-Jettronic
Schaltplan Siemens MS40
Schaltplan Motronik vom 535i

and a lot more there. Probably one of the best pages, just the instructions how to change from the clock to OBC covers about 60 pages, lot's of pics.
Check it out