You're looking for a Stromlaufplan (which is German for "wiring diagram" or "electric circuit diagram") for an Audi A4 (8E)!
Official Audi Service Portals: The most accurate source is Audi erWin, where you can access official factory manuals, including detailed electrical schematics, via a time-based subscription. stromlaufplan audi a4 8e pdf downloadl top
: While labeled B5, it includes diagrams for ignition, starter, and main fuse configurations relevant to early 8E architecture. Professional & Detailed Manuals KFZ-Verlag via eBay You're looking for a Stromlaufplan (which is German
Start your download today, print the relevant pages (B4 or larger), and tack them to your garage wall – you’ll wonder how you ever worked on your Audi without them. including detailed electrical schematics