shogun/yaofeng, thanks for the link and help. i went and download the link provided for the 93 model - after reading it i notice:
1. it doesn't show wiring for a 520i (only 525 & above)
2. when i just compared the fuse/relay box (for 525), it is very different from what i have in my 520i.
3. the power distribution for 525i looks different from mine.

is there a ETM for 520i model?

Quote Originally Posted by shogun
Yaofeng is right: You have to study that, all answers are inside
http://shark.armchair.mb.ca/~dave/BMW/e34/
If you try such a modification, you have to understand it and that only goes by studying the ETM.
Every aplice of wire is shown there and all connections, and also a component location section with pics.