Commando wiring system

Hi Mike, the diagram looks fine to me. One issue may be the need for the brake light to be operated from both the front and rear brake levers. This is always a contentious issue and seems to be machine-age related and the rules seem difficult to decipher. Some MoT testers can be a bit strict on this. I found this when I changed some wiring on my 1971 BSA Rocket 3.

My local MoT man allowed my bike to pass with just one of the two brake switches functioning. I was a bit surprised at this and querried his decision. However he is very experienced and said that as long as either one worked that was fine for him.

The wiring diagram looks correct but having never used a Power Box I need to ask if it actually does have a separate source for the lights? My A1 Box just has two wires out going straight to the battery.

Commonly on older bikes the brake light runs direct from the battery and not through the ammeter. It makes sense for three reasons: one is that it is intermittently used and the ammeter really tells you if the charger is keeping up with the discharge for most (not all) of the time; and secondly because it saves wire, and thirdly because it reduces the number of connections and simplifies the 'rat's nest'. It also makes it that much easier to wire up.I wish I'd realised that before I recently wired my own new brake on an old bike. A ten minute job took (quite unnecessarily) well over an hour as a result.

If the ignition switch cuts the lights then you won't be able to use a parking light - including lighting up the shed when you park on dead engine. Or if stopped at night to read a map etc etc. It's unusual...