Norton Commando Wiring Diagram + Podtronics

Grant Tiller

I am in the process of adding a few different circuit diagrams to the site.

One of the most common upgrades or modifications for a classic british bike is to add a combined regulator/rectifier unit.

Our Commandos use a blue can capacitor, zener diode (which can be found mounted on the back of the z-plate) and rectifier unit.

A combined regulator/rectifier replaces all of these components with one package.

The most common manufacturer of these is Podtronics.

Grant Tiller

There are four wires to connect:

  • Two Yellows – these are the AC input and pick up on the Green/Yellow and Green/White (connection can be any way round, as this is the AC side of the circuit)
  • The Red – this is the Positive output and will join to the red wire if you are using existing wiring (it goes straight to the ground/earth of the frame)
  • The Black – this is the Negative output (known as the hot wire) – it will pick up on the Brown/Blue wire (which goes via a fuse straight to the battery negative terminal)

Here is a factory wiring diagram with the Podtronics unit added into the circuit.

Pre-1971 (ammeter in the headlight shell and Wipac Tricon type handlebar switch) PNG 3066×1841

Grant Tiller

1971 (three wires to the master switch) PNG 3066×1841

Grant Tiller

1972 onwards (four wires to the master switch) PNG 3066×1841

Grant Tiller

1974 MK3 Early Bikes – there were around 2,000 bikes that were built around the December 1974 timeframe that have three additional fuses that can be found in the headlamp bucket.

These bikes are also wired with the old Lucas 3AW 3 wire ‘silver can’ assimilator.

1974 MK3 (Early) PNG 3066×1841

Grant Tiller

1975 MK3 this is the most common configuration, and takes us through to the final Commando that rolls off the production line.

1975 MK3 (Original) PNG 3066×1841

Grant Tiller

1975 MK3 Canadian Market – there were legal requirement in Canada around the headlamp being on while the engine was running, so the wiring diagram includes changes needed (swapping out the Warning Light Assimilator 06-6393 for the Headlamp Warning Unit 06-6392). Note that a different Master Switch is also required.

This is covered in the Factory Wiring Diagram, by notes.

1975 MK3 (Canadian Market) PNG 3066×1841

Grant Tiller


A couple of points about the way these diagrams have been drawn:

  1. Where the same colour wire goes in to and out of a single connector, that connector has usually been omitted from the drawing.
    It’s obvious on the bike, is easy to spot and easy to troubleshoot.
    Leaving them off the diagrams makes them a LOT easier to read, and considerably less cluttered.
  2. Wherever the earth or ground side of a component goes back to the battery, the drawing shows a red earth symbol:
    Grant Tiller
    In reality, this could be connected either to a red wire in the bike’s wiring harness (loom) OR it could be attached to the frame or engine of the bike.

    I have shown the red earth symbol each time in order to massively simplify the diagram, and make it a lot easier to understand for everyone.

    I have also coloured them red as a gentle reminder that these bikes are wired positive earth!

I hope these will be useful to someone!

Warning Light Assimilators

It is important to note that MOST aftermarket reg/rec manufacturers do not support either the pre-MK3 Lucas 3AW silver can warning light assimilator OR the MK3 one.

Boyer Bransden are very explicit in their instructions for the Power Bow – they have even made an alternative Power Box model that includes a charge warning light.

Other manufacturers (PODtronics, SPARX and the Tri-Spark MOSFET units) either mention it in their smallprint/FAQs or neglect to mention it at all.

As such, I would recommend NOT using the original assimilator and consider your alternatives.

You could replace your assimilator with a solid state equivalent like the CoolCat Express (warning: you have to buy positive SS3AW-P or negative SS3AW earth)

Alternatively, you could follow my recommendation and buy a Charge Warning Light instead.

A warning light assimilator tells you that the alternator stator is producing an AC output, whereas a Charge Warning Light tells you that the battery is charging, the reg/rec is working and it gives you much more useful information about performance of the charging system and the state of charge.

I personally recommend the Improving Classic Motorcycles “Standard” Charge Warning Light. This model wires in to the standard incandescent lamp, so it looks better than a modern LED. It matches all your other warning lamps, which is particularly important on the MK3 with it’s instrument ‘console’

The ‘brainbox’ is about the size of a postage stamp, and can easily live inside the headlight bucket or under the MK3 ‘console’

3 replies

  1. Hi Grant, many thanks for making these great wiring diagrams available to us, much appreciated.
    Just wondering if you could please do one for me that shows 3 phase alternator, Podtronics unit, Tri Spark ign and Colorado Norton Works single double output coil? I would be grateful if you could do this for me
    Kind regards
    New Zealand

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