Main loom wiring

Forums

Hi ,

I’m hoping someone can help. I’m reaching the end of a rebuild of a Fastback, built in November 1971 according to the build plate. However, it was a bit of a basket case with very little in the way of electrical parts. I have just bought a Lucas main wiring harness for ( it says ) 1970 - 74 Commandos. The wiring diagram in a Clymer book I have shows a 3 position master switch for this year using a brown and blue lead, a white lead and a brown and green lead but the Lucas harness also has a blue and yellow lead for the master switch. Should this bike have a 3 position switch and if so do I ignore the blue and yellow lead. ?

Also, I believe there should be a switch in the headlamp, is this a 2 position switch and what does it do?

Is there a better diagram available or has someone else also had a problem using this harness which covers a number of years?

Many thanks,

Phil Norris

If you have the new Lucas…

If you have the new Lucas cloth loom be aware there are two errors in the included schematic .

The 3 leads labeled blue lamp flasher are for the Warning Light Assimilator and the 2 leads labeled Warning Light Assimilator are for the power point socket.

Commando ignition switch wiring

Don't know if this helps, but I built my Commando/Featherbed from scratch way back in 1978 and vividly remember having much 'fun' trying to make my own wiring harness. I still have the Haynes manual I used to make mine, which shows that blue and yellow lead was only used on the 4 position master switch on post 72 Commandos. It goes to the 2-way switch in the headlamp that you mention, and it is the power feed for dip/main beam. By the way, I ran my bike for over 30 years so I couldn't have made that bad a job of the wiring! Good luck with yours.

BLU/YLW

The BLU/YLW wire, yes this does feed the main beam but in the wiring schematic this colour is. always 'ignition switched power feed for head light' would only be used where the 4 way Ignition is used and switches the lights off. The two way headlight switch would be 'Side or main lights' The BLU/YLW is used on the later years Triumphs ie any 4 position ignition switch that controls lights.

If you have just the two way ignition switch then the BLU/YLW wouldn't be used and the feed from the 3 way toggle light switch would be BLU

Thanks very much Richard and…

Thanks very much Richard and Mark for your comments and info, very useful.
I had a Fastback in the late seventies/eighties and vaguely remember that the ignition/master switch down by the L/H side panel only had an “on/off” function and a 3 position switch on the headlamp:- lights off - side lights - dip beam, main beam on handlebar switch. Is my memory right?

Does anyone have a wiring diagram for a late 1971 Fastback?

Many thanks,

Phil Norris