Norton Commando Ignition Switch

Grant Tiller

The Norton Commando Ignition Switch is referred to as the Master Switch in the Workshop Manual.

Up until the MK3, it can be found above the left side footrest.

For the MK3 it was relocated to the Warning Light Console in front of the handlebars (the wiring is still the same though)

Grant Tiller

From 1972 onwards a four terminal, four position switch was used – Lucas Part Number LU30552.

The positions are:

  1. Parking with Lights (key removable)
  2. Off (key removable)
  3. Ignition Only (key captive)
  4. Ignition and Lights (key captive)

The numbers on the factory wiring diagram correspond to the numbers embossed on the bottom of the switch itself.

Here is an excerpt from the wiring diagram, showing the colour of the wires going in to the switch.

Grant Tiller

Here you can find the entire Norton Commando Wiring Diagram (there are many different versions on this website which will cover all years, as well as many of the popular upgrades)

Grant Tiller

One point worthy of note – Bill Turnbill produced a colour coded wiring diagram (from where my first ones were reproduced from with his kind permission)

Bill’s diagram incorrectly labels terminals 3 and 4 (they are shown reversed on his diagram)

Grant Tiller

You will notice that the bottom of the Lucas LU30552 switch is numbered 1, 4, 2 and 3

So when you plug your cables in on the bike, be careful how this relates to the diagram (both mine as well as the ones in the factory workshop manual) which numbers 1, 4, 3 and 2.

  • 1 NU (Brown and Blue)
  • 4 UY (Blue and Yellow) – this is the single terminal
  • 2 W (White)
  • 3 NG (Brown and Green)

Hopefully this will help somebody!

8 replies

  1. Hi Grant, I am rewiring a ’74 Roadster. I’m in Oz but the bike is a U.S. import. I replied to you a couple of days ago about the Lucas/Wassell main wiring loom for the ’74.

    I have a query on the ignition (master) switch that is on the wiring loom I removed from the bike. I’m thinking it may not be a Norton part.

    Visual Description: It has 3 x metal studs that protrude from the rear of the switch. The wires from the harness are attached to these small studs with nuts by (what we call in Oz) Ring or Eye terminals and then the nuts screw on the studs to hold them in place. I’d send a pic but I don’t think I can on this forum.

    Operation of Switch: The switch has 3 positions. After the key is inserted into the lock it can be turned CCW which connects power to the ACC post/stud only (key cannot be removed). Turn it CW and this is the OFF position (the key can be removed). Turn the key one more position CW and this activates the 3rd post/stud labelled IGN and also the ACC post as well. The key can from this position be turned CW against spring pressure (a bit like an action to activate a starter on an old car), when pressure ir released it pops back again. In these last two positions the key cannot be removed. When the starter type action is operated there is power to the IGN post but not to the ACC post/terminal.

    In my case 2 x brown/blue NU wires are connected to the BATT terminal. 2 x brown/green NG, 2 x white W and 1 x green/yellow GY are connected to the IGN terminal. There are no wires connected to the ACC terminal.

    BIG QUESTION: Do you know what it is off? Is it Norton? Would I be better getting a new Lucas Master Switch?

    Thanks for any advice you can give me Grant.

    Cheers Don

    • Hi Don,

      I think you’re right, it doesn’t sound like a Norton switch.

      There were many that looked similar of the time, but had a different number of positions or terminals.

      On your 74, it would have had four terminals and four positions – the same through until the end of MK3 production.
      (The 1971 model had three positions and three sets of terminals)
      (The 1968-1970 models were simple on-off switches with two sets of terminals)

      The more common switch type is the triumph one, which you see more frequently sold by aftermarket resellers.
      However, it sounds like your switch is not one of these, as they did not have the momentary spring loaded starter position.

      On the Commando harness there are a lot of wires that come together in this switch.
      To be honest with you, I would prefer to see the correct switch in place, as it is better suited to handle the amps of the lighting.
      (the contacts inside these switches are quite small, so by having more positions, it means that the load can be spread more evenly across different sets of contacts, which in turn makes the switch more reliable)

      Since you have invested in a new harness, it would be a shame to start butchering it up to make it fit your switch.

      …sorry, it means spending more money $$$ but I do feel it is worth doing.

  2. Hi Grant,

    Thanks for your thorough reply. Yes I will get a new master switch from AN.

    I am planning on eliminating the blue capacitor and the warning light assimilator. I have purchased both a 1x CWL+, 1x CWL+LED to fit as a replacement for the assimilator from ICM in UK. I am disposing of the 2 x ign coils and bracket and fitting a Pazon Dual Output Digital ign coil with a Boyer electronic ign — so no ballast resistor, condensor pack, breakers, etc. The zenor and rectifier will be replaced with a more modern unit.

    Any further advice for me or a wiring diagram you can point me towards.

    Thanks so much,
    Don

  3. Thanks Grant — Appreciated
    Last question I hope!! If you can help and I’m sure you can in relation to my electronic ign.
    Both the Boyer electronic ign and the Pazon dual outlet digital coil are used parts and have been gifted to me.
    I need to be sure they will work together ok.
    The electronic ign is Boyer BOX00232 and the Pazon PVL Dual Output Digital Ignition Coil (1290005).
    The coil’s primary resistance is 0.6Ω and secondary resistance is 8.08KΩ as measured by me.
    I have read elsewhere that coils with primary resistance of between 3Ω and 4.5Ω are required in some applications.
    Could you clear this up for me please? Will my setup work satisfactorily?
    Thanks
    Don

    • Hi Don,

      BOX00232 is the Micro Power system – (we commonly refer to it as the Boyer Blue Box)
      This kit is different from most of the other systems in the market, in that it comes with it’s own dual output coil.

      The primary resistance of between 3Ω and 4.5Ω is a requirement for the more common analogue Boyer MKIV which is built around the idea of using a pair of the original Lucas 17M6 (LU47275) coils.

      It was definitely worth checking, but it sounds like you have nothing to worry about here, and you’re good to go!

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