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1972 Norton Commando Electrics/Ignition #705556
08/20/17 3:59 pm
08/20/17 3:59 pm
Joined: Nov 2015
Posts: 29
Penna
D
Dnaj11 Offline OP
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Dnaj11  Offline OP
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Joined: Nov 2015
Posts: 29
Penna
I've bringing to life a 72 Commando but the wiring looks kinda weird. With a battery at positive ground and get voltage on blue/brown at the ignition switch but weird readings on the switch with the key turned on, so I jumpered the switch with the key off and I get hot coils and spark at the plug -good sign. I get nothing much elsewhere in any key position. Looking at the wiring harness, (and I have seen the diagram) I see a lot that looks changed with open connectors. I've circled them in the below photos. Looks to me like someone changed the grounds and some other connectors. Can anyone make sense of this based on plug location and colors?

[img]http://goo.gl/photos/y2RwY1F8ay9sgsPP8[/img]
[img]http://goo.gl/photos/AzCTrJXi31Ys35Qk8[/img]
[img]http://goo.gl/photos/S1k8WLsomeYs9DSQ6[/img]

Last edited by Dnaj11; 08/20/17 4:02 pm.
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Re: 1972 Norton Commando Electrics/Ignition [Re: Dnaj11] #705564
08/20/17 5:00 pm
08/20/17 5:00 pm
Joined: Mar 2006
Posts: 3,565
Norfolk, UK
L.A.B. Offline
BritBike Forum member
L.A.B.  Offline
BritBike Forum member
Joined: Mar 2006
Posts: 3,565
Norfolk, UK
Originally Posted by Dnaj11
I've bringing to life a 72 Commando but the wiring looks kinda weird. With a battery at positive ground and get voltage on blue/brown at the ignition switch but weird readings on the switch with the key turned on, so I jumpered the switch with the key off and I get hot coils and spark at the plug -good sign.


The ignition switch can become corroded inside. It can be dismantled and cleaned (or just replace it?).


Originally Posted by Dnaj11
I get nothing much elsewhere in any key position. Looking at the wiring harness, (and I have seen the diagram) I see a lot that looks changed with open connectors. I've circled them in the below photos. Looks to me like someone changed the grounds and some other connectors. Can anyone make sense of this based on plug location and colors?


There will also be some unused wires in the standard harness.
Unfortunately, the photos are too blurred and the wires too dirty to tell much as the colours don't stand out except for the green, so perhaps you could say what the colours are? Nevertheless I will have a go, but some more detailed information would be useful.


1st. photo
The 'green' on the right could be the flasher relay light green/brown that goes to one of the handlebar switch clusters (could be either the left or the right)? The rest I can't tell as I can't identify what colour they are. Note the large rubber connector block in that photo at the right hand side should definitely be replaced.


2nd. photo
A 'green' and other wires? Possibly the assimilator wires if the green is actually green/yellow?



3rd. photo
One looks as if it could be a white/purple? If it is, then it's an unused wire. If the other happens to be a white/red then that is also an unused wire.

There seems to be an extra emergency starting capacitor.

Last edited by L.A.B.; 08/20/17 5:08 pm.
Re: 1972 Norton Commando Electrics/Ignition [Re: Dnaj11] #705565
08/20/17 5:02 pm
08/20/17 5:02 pm
Joined: Jun 2002
Posts: 9,690
Scotland
S
Stuart Offline
BritBike Forum member
Stuart  Offline
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S
Joined: Jun 2002
Posts: 9,690
Scotland
Hi,

Originally Posted by Dnaj11
72 Commando
battery at positive ground and get voltage on blue/brown at the ignition switch but weird readings on the switch with the key turned on,

Standard 4-key-position switch? Male spade terminals, three doubles and a single? Numbers 1-4 stamped in the brown terminal backing beside each terminal?

If all of that, and the wires on the correct terminals according to the diagram (1 - Brown/Blue, 2 - White, 3 - Brown/Green), "weird readings" sometimes just because the internal contacts are corroded. It's possible to (carefully) prise the brown base out of the metal body, clean and lube the contacts, reassemble and it all works properly again. bigt

Originally Posted by Dnaj11
jumpered the switch with the key off and I get hot coils and spark at the plug -good sign. I get nothing much elsewhere in any key position.

You "jumpered" Brown/Blue to White? As well as "hot coils and spark at the plug", things like turn signals, brake light, horn, headlamp flash should all work - turn signal relay and everything else supplied by White wires.

If you "jumper" Brown/Blue to Brown/Green, you should see pilot, tail, speedo. 'n' tacho. lights; if you twist the headlamp on/off switch on the headlamp shell, you should get main or dip depending on the handlebar paddle switch setting.

Originally Posted by Dnaj11
I see a lot that looks changed with open connectors. I've circled them in the below photos.

Pending someone along who sees the colours better than I do, could you also tell us the wire colours in each picture? Pictures don't always show both colours on a wire if there's more than one, colours have faded and/or got dirty in 45 years, different computer monitors render colours differently (particularly faded and/or dirty ones ...).

Hth.

Regards,

Re: 1972 Norton Commando Electrics/Ignition [Re: Stuart] #705567
08/20/17 5:27 pm
08/20/17 5:27 pm
Joined: Mar 2006
Posts: 3,565
Norfolk, UK
L.A.B. Offline
BritBike Forum member
L.A.B.  Offline
BritBike Forum member
Joined: Mar 2006
Posts: 3,565
Norfolk, UK
Originally Posted by Stuart
Standard 4-key-position switch? Male spade terminals, three doubles and a single? Numbers 1-4 stamped in the brown terminal backing beside each terminal?

If all of that, and the wires on the correct terminals according to the diagram (1 - Brown/Blue, 2 - White, 3 - Brown/Green)


That would be for a '71 Commando with the 3 terminal switch.

A 72 Commando is more likely to have the 4 terminal switch so has an additional blue/yellow wire to T4.

[Linked Image]

Last edited by L.A.B.; 08/20/17 5:32 pm.
Re: 1972 Norton Commando Electrics/Ignition [Re: Stuart] #705568
08/20/17 5:27 pm
08/20/17 5:27 pm
Joined: Nov 2015
Posts: 29
Penna
D
Dnaj11 Offline OP
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Dnaj11  Offline OP
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Joined: Nov 2015
Posts: 29
Penna
That's a help. Thanks. Here's more.

Photo one: right side circled area, open wires colors: three wires with male round bullets - green+purple, brown+black, brown+maybe something; left hand circle: two white+red strip with female spades

Photo two: I'm guessing its the other end of the above three colors wrapped in electrical tape

Photo three: white+red and white+purple, also with female spades

Re: 1972 Norton Commando Electrics/Ignition [Re: Dnaj11] #705572
08/20/17 5:59 pm
08/20/17 5:59 pm
Joined: Mar 2006
Posts: 3,565
Norfolk, UK
L.A.B. Offline
BritBike Forum member
L.A.B.  Offline
BritBike Forum member
Joined: Mar 2006
Posts: 3,565
Norfolk, UK
Originally Posted by Dnaj11
Photo one: right side circled area, open wires colors: three wires with male round bullets - green+purple, brown+black, brown+maybe something;


Commando Interpol (police/military) model wires, so unused.



Originally Posted by Dnaj11
left hand circle: two white+red strip with female spades


Unused.


Originally Posted by Dnaj11
Photo two: I'm guessing its the other end of the above three colors wrapped in electrical tape


Same as first answer.

Originally Posted by Dnaj11
Photo three: white+red and white+purple, also with female spades


Unused.

You should also find a white/red connected to one of the switch clusters. Although that white/red wire basically goes nowhere and the pushbutton has no standard function the white/red will become live/hot when the button is pressed so make sure the connector is insulated.

Last edited by L.A.B.; 08/20/17 6:08 pm.
Re: 1972 Norton Commando Electrics/Ignition [Re: Dnaj11] #705580
08/20/17 8:32 pm
08/20/17 8:32 pm
Joined: Aug 2001
Posts: 888
Annapolis, MD
Dennis B, R.I.P. Offline
BritBike Forum member
Dennis B, R.I.P.  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 888
Annapolis, MD
On a 72 you should have the 4 position switch
all the way to the left (counter clockwise) is the park position
pilot lamp on and key can be removed
next position to the right is the OFF position, nothing on, key can be removed
next position to the right is the Daytime ON position, key can not be removed
next and last is night time ON position
Taillight on, key can't be removed
you should have spark in either ON positions
HTH
Cheers
Dennis B


Member # 182
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