Hi there, if anyone's interested i've drawn up a wiring diagram for a project i'm doing on a series 3 (using the m-unit blue).
Used an m-unit blue on a classic motorcycle that had been giving me electrical issues for years and it was transformative. 100% reliable, easy to configure and with the added bonus of adding a secure built in alarm.
There's a handy article of someone who's done it on an mini cooper - Mini Cooper 1964 Digital Electrics | Stuntex - Motorcycle Video Magazine
If you pair it with an High Load MSD solid state relay kit for the high load bits (headlights, glow plugs, heated windscreen etc), then you can make it work.
This is the wiring diagram i've drawn up based on adapting the factory wiring setup. As you can see there's only two fuses, which I might replace with circuit breakers.
https://ibb.co/Xt92fnS
