The below article was written to furnish THREE types of information:
(1) CONSIDERABLE amount of BASIC & SLIGHTLY ADVANCED INFORMATION on electricity & Airhead problems. The approach used here is probably different than in most manuals & troubleshooting guides. Although some hints are given in this article on some common faults, this article should be used in conjunction with my other articles, particularly: http://bmwmotorcycletech.info/electricalhints.htm
(2) Common problem areas, explanations of some of the circuitry. A discussion of such as batteries; starter motors, voltage regulators, etc. Other articles will get far deeper into these things.
(3) An addendum that may discuss particular points that has come up, or some topic of interest. Some is at the very end of this article.
Available to you are certain helpful booklets from such as Motorrad Elektrik, Chitech, Haynes and/or Clymers manuals (and, perhaps, a schematic in the rear of your owners booklet or on the Snowbum website). In my opinion the Chitech electrics manual and the owners book or factory schematic, or schematics on the Snowbum website (and some elsewhere’s, and I have links to these on the Snowbum website), are THE BEST sources for electrical information for the Airheads.
I recommend you at least purchase at the Chitech Electrics Manual. The Chitech (Chicago Region BMW Owners Assoc.) BMW Electric School Manual is THE BEST manual for BMW electrics, from basics to full-blown technical details, components, diagrams, etc., & includes the singles & all Airheads; even some on the /2 era. It is VERY complete. Only a few errors, for which i wrote an article/Critique: http://bmwmotorcycletech.info/chitechelmnl.htm
See http://bmwmotorcycletech.info/url.htm for more information on Chitech, and how to order their publication. Some of the total-bike schematics are not reproduced well, that is the only substantial problem with that manual. Get the manual anyway.