Can you tell me what software is good (i.e., free) for generating wiring diagrams. I'm contemplating doing one for my bike with MotoGadget M-Unit Blue, if someone could provide me with a file. Thanks,
Frey

I think TinyCad will do that. Its open source.

Also, here's a list of other options.

Carl Allison on ThisOldTractor fame used ACD Systems Canvas to maintain all the wiring diagrams he produced for the Moto Guzzi marque. I don't believe that program is freeware and requires licensing.

I am sure that Draftsight by Dassault Systems would be capable.  I have used it for years as a free alternative to AutoCAD and it has been flawless for me.