I came across this website for the first time and didn't find any link posted on this forum, so I thought I'd throw it out there.
The header for the site says "BMW Technical Information System"
https://www.newtis.info/
It appears to have BMW manual links by Series including:
- Repair Manuals and Technical Data
- Wiring Diagrams and Functional
- Electrical Components / Conectors
There is a disclaimer that it is not affiliated with BMW or an official source, but looks pretty legit. I've never seen the actual TIS, so I'm not sure how it compares.