Having just checked it seems the 3.7 Roadster BCU has strong similarities with Plus 4. The connectors and wiring for sidelight controls correlate for example. This may help therefore.

[Linked Image]

ETA: full 2014 on parts book in pdf format (which offers better resolution wiring diagrams) here.

Last edited by Richard Wood; 28/10/19 10:37 AM.
Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone