Ignition Switch Wiring

I am confused about my Ignition Switch. The bike was fired up by the PO when I bought it, ran ok. I am cleaning, rebuilding, replacing. and LEARNING.

The ignition switch wiring looks different than the schematic. There is a ridge on the top of the switch, which I have shown on my sloppy diagram.

1...When you look at the schematic, I assume you are looking at the back of switch. Correct?

2...The back of my switch is wired differently than the schematic shows. White and Brown/Green are swiped. Which way should I wire it?

3...I don't feel ready to completly rewire right now; I want to get this thing on the road in the spring. Can I clean the blade terminals with Acetone and reassemble?

If you have the std. 4 pos switch these terminals should be connected as follows.....
Parking lights: 1 click left = 1 & 3 connected.
Off: 2 & 3 connected.
Ign: 1 click right = 1 & 2 connected.
Ign and all lights: 2 clicks right = all connected.
I'd say with 2 and 3 reversed you shouldn't have ignition at 1 click right but you would have parking lights. 1 click left would give you ignition instead of park lights. So, 2 clicks right would give you all functions as normal. Why dont you check continuity with a bulb or meter for all 4 positions, then you'll know if you have the correct switch.

Some of the aftermarket switches use a different terminal for the power feed than the original Lucas model, as Keith says simply check with an ammeter or a battery and bulb for the appropriate internal connections.

And don't forget that at positions 1 and 2 you can take the key out, but on positions 3 (ign) and 4 (ign + lights) you can't. I've just gon through this with my '71, and I used a meter to check continuity and determine which switch terminal was which.
If I remember rightly, on Position 4 all terminals are connected, position 3 the feed and ignition only are connected, position 2 nothing is connected, and position 1 the feed and pilot (parking) light terminals are connected.

dave M said:

Some of the aftermarket switches use a different terminal for the power feed than the original Lucas model, as Keith says simply check with an ammeter or a battery and bulb for the appropriate internal connections.

Click to expand...

On member rgrigutis' switch, it was the number 3 & 4 terminals that needed the wires swapping over: post37968.html

Thanks, L.A.B.

I missed this thread on my search before I posted. The first thing I noticed when I pulled the black cover to the ignition was that Brown/Blue showed some melting.

Thanks a bunch.

Hi Herman,
My 750 made in september 72 is wired as the top of your picture & NOT as it says in the manual.
I just made a note of where the wires were when I put a new switch on & re wired it the same as before.
I have a Boyer power box on mine & a boyer electronic ignition but I dont know if the wireing is different because of this.
Mine works fine like this. All the lights work & the key comes out in last position for parking lights without ignition on.

Your Terminal 4 with yellow/blue is only a single terminal on mine
Next going clockwise your 3 is white on mine
next clockwise your 2 is Brown/Green on mine
Next clockwise your 1 is Brown/Blue on mine
There is a slightly bigger gap between your terminals 2 & 1 on mine going clockwise.

My wires were original & perished so I put a complete new harness on as the wires were burning out when I put the lights on.
I hope this helps, best of luck.
Cheers Don

Don Tovey said:

My 750 made in september 72 is wired as the top of your picture & NOT as it says in the manual.
I just made a note of where the wires were when I put a new switch on & re wired it the same as before.

Your Terminal 4 with yellow/blue is only a single terminal on mine
Next going clockwise your 3 is white on mine
next clockwise your 2 is Brown/Green on mine
Next clockwise your 1 is Brown/Blue on mine
There is a slightly bigger gap between your terminals 2 & 1 on mine going clockwise.

Click to expand...

In which case your 'new' switch was probably a 'Lucas' item, and not a pattern one, as pattern switches frequently have 8 spades, (double T4), so you would have connected it according to the manual, as the original Lucas switch terminals are in different positions compared to some of the pattern ones, so the terminal number sequence on the Lucas switches doesn't actually match the wiring diagram, as some pattern switches do!

Yes, thats how my switch is wired & everything works fine.
It seems daft to me that the manual is wrong when as far as I know Lucas switches were a standard item when the bike was new.
Still thats Norton for you. There are about 3 different wireing diagrams in my manual for different year models but mine was made in swept 72 & Neville Hintons factory records have it as a 1973 model.
I got my wireing Harness from Fair Spares in UK a few years ago before I left bike in garage for 5 years because I could not be bothered to strip & rewire it. I did it eventually though & i'm now glad I got it going again. It has more character than my Suzuki. Although it wont do 150mph like the bandit will.
Cheers all

I just went thorugh a similar trauma with my 850 - I was fortunate enough to have a genuine new Lucas switch in the box of bits that came with the bike, and I ended up going back to good old continuity checking with a multimeter to get the effing thing to work!

The old lock is still OK but with no key - do the numbers on the side mean anything relating to the key? ISTR that on Triumph locks the tumbler had to be pulled before the number could be read....and you needed the key to get the tumbler out

Now I need to find a place to store all those unused Interpol connections - what's that all about? :roll:

I had a real problem w/ mine but the forum walked me thru it. Once I figured out how to ohm out the switch things worked like they were intended to. Except the tail light wouldn't come on in the 4 th position. Checked connections and all was good. Bought a new switch and tail lite works now. However new switch had the hole that accepts the tumbledr detent misdrilled so I had to use a dremel to elongate the hole enough for the detent to engage. The Lucas jokes are beginning to find meaning for me.

I searched and read and read some more. This thread seems to be the best for this question so here is my problem. My switch does not seem to match the one shown. Bike is a 73 850. Back of the switch looks like this.

broken link removed

The double lug at 11:00 and 12:00 is labeled #1
The Single lug at 2:00 is labeled #3
The double lug at 8:00 and 9:00 is labeled #2

There is no terminal at #4

My wires are Brown+Blue, Brown+green, White and Yellow+blue. The White, Brown+Blue and Brown+green are all double wires.
It is a 4 position switch.

Can someone tell me what wire goes where?

I think somebody has fitted an early 3 terminal switch to your 850 in place of the correct 4 terminal one?

So you'd need to connect the wires according to this diagram: http://rocbo.lautre.net/technique/norto ... p/150.html -and the Blue/Yellow headlamp wire will have to share terminal 3 with the Brown/Green.

Alternatively, fit the correct 4 terminal switch, so that Blue/Yellow will have its own terminal (4) : http://rocbo.lautre.net/technique/norto ... p/151.html

Sadly thats what I thought. I have never been able to get the cafe lights to work correctly and I have had other electrical gremilins. I just recently fitted a new WL assimilator and the red light only glows red in one position and that is the only position that the bike will run. No lights in that position though.

I will get a new switch and return all of the wiring to as close to original as I can. I also have a tympanium and a Boyer so it won't be completely original but hopefully I'll get the lights working correctly.

Thanks.