Headlight Switch Wiring

WEM · Jan 23, 2020

I have a 1974 Roadster which I'm pretty sure has stock headlight wiring. Certainly looks original. The headlight toggle switch has four spade connectors on it, two on top and two on bottom. There are two wires that connect to the switch, a solid blue wire and a blue wire with white stripe. I'm not sure how the wires connect. My question is: do the two wires connect to the top two spade connectors, to the bottom two spade connectors or does it even matter if they connect to the top or bottom spade connectors? If anyone has a photo of the inside of their headlight shell showing the connections, that would be a great help.

L.A.B. · Jan 23, 2020

WEM said:
There are two wires that connect to the switch, a solid blue wire and a blue wire with white stripe.

Should be blue and a blue/yellow.

WEM said:
I'm not sure how the wires connect. My question is: do the two wires connect to the top two spade connectors, to the bottom two spade connectors or does it even matter if they connect to the top or bottom spade connectors?

It shouldn't matter as all the switch does is connect blue to blue/yellow but attaching the wires to the bottom two spades (if that works) should reduce the possibility of the bare terminals shorting to the reflector etc (assuming the wire terminals are insulated?).

Tornado · Jan 23, 2020

Just check the switch contacts with an Ohm meter to confirm which two give the closed circuit when switch is in desired position, either straight up or over to the side. I think one pair closes while other pair opens as switch is toggled. I like switch set to straight up position for light to be on.

Richard Tool · Jan 23, 2020

Tornado said:
Just check the switch contacts with an Ohm meter to confirm which two give the closed circuit when switch is in desired position, either straight up or over to the side. I think one pair closes while other pair opens as switch is toggled. I like switch set to straight up position for light to be on.

This is correct as I just tested mine an hour ago

WEM · Jan 23, 2020

I just had another look and confirmed that L.A.B. is correct; the two wires to the switch are indeed solid blue and blue/yellow. Not sure how I missed that when I first looked. I'll check the switch tomorrow with my meter as suggested. Thanks for the assistance.

Tornado · Jan 23, 2020

WEM said:
I just had another look and confirmed that L.A.B. is correct; the two wires to the switch are indeed solid blue and blue/yellow. Not sure how I missed that when I first looked. I'll check the switch tomorrow with my meter as suggested. Thanks for the assistance.

I've yet to see an incorrect call from Mr. LAB.

L.A.B. · Jan 24, 2020

Tornado said:
I've yet to see an incorrect call from Mr. LAB.

It has been known to happen.

WEM said:
I'll check the switch tomorrow with my meter as suggested.

An original 71-74 headlamp switch should be a Lucas two-position 34660(B). I don't have a 34660 to check but I believe with the wires attached to the lower terminals (5 & 6 as the terminal positions are numbered 1- 8 even though some don't have a spade) the switch will be ON with the toggle in the central position. With the wires connected to the upper terminals (7 & 8), the central position is OFF.

The replacement switch is 31780 which has a different terminal layout.
https://andover-norton.co.uk/en/shop-details/17438/lighting-switch-2-position-34660-lucas-

maylar · Jan 24, 2020

Tornado said:
I like switch set to straight up position for light to be on.

The rider's manual says otherwise...

L.A.B. · Jan 24, 2020

maylar said:
The rider's manual says otherwise...

View attachment 14105

Yes, but, the rider's manual is wrong as that's for the pre-71 three-position switch (35710) which operates the lights.

The 71-74 two-position switch only selects headlamp ON-OFF. Edit: The ignition switch must also be at the 'ignition and lights' position for the headlamp to work.

Other lights (pilot, tail, instruments) are switched on-off at the ignition switch.

maylar · Jan 24, 2020

L.A.B. said:
Other lights (pilot, tail, instruments) are switched on-off at the ignition switch.

Right, I was gonna mention that. It was copied from the 750-850 rider's manual. I guess it should read, "In the left position parking and tail lights, in the right position parking, tail, and headlights", with some mention that the key switch has to be in lights position too.

... At least, that's how mine is wired. But, to each his own.

L.A.B. · Jan 24, 2020

maylar said:
I guess it should read, "In the left position parking and tail lights, in the right position parking, tail, and headlights", with some mention that the key switch has to be in lights position too.

Not exactly, as the headlamp switch is nothing to do with 'parking lights' as that is selected at the ignition switch.

The two-position headlamp switch only functions to turn the headlamp on or off once 'ignition and lights' has been selected at the ignition switch so read HEAD - PILOT as the 850 Mk3 handlebar switch does.

Tornado · Jan 24, 2020

Saying left or right position for the two position switch is a little unclear as the switch only has a straight up or to one side position. The earlier three position switch has left/center/right positions.

Reason I prefer centre position for lights on, it gives the lowest aerodynamic drag at speed

marshg246 · Jan 25, 2020

Whether two- or three-way, the headlight toggle switch has 8 possible terminals. Some terminals are left off each type. AFAIK internally they all work the same. Properly installed on a Norton, a two-way switch is either straight up or towards the timing (right) side. If you look carefully you should see that the terminals are numbered.

Terminals 1, 3, 5, 7 are all connected together so one of you wires goes there.
Middle position (straight up) 2, 6 connect to the common terminals (1, 3, 5, 7)
Right position (timing side) 4, 8 connect to the common terminals (1, 3, 5, 7)

Left position (to drive side, if any) 4, 6 connect to the common terminals (1, 3, 5, 7)

On a Norton, normally, one wire goes to 1 (or 7) the other wire goes to 8. If you want it backwards, and you have a new "Genuine Lucas" two-way switch, you connect to 1 (or 7) and 6.

If you have a three-way switch, it will work fine. Connect it as a normal two-way switch and ignore the fact that it can flip to the left.

The drawing is for a Triumph that does use a three-way switch and it controls the parking lights as well as the headlight. On a Norton, the label for the right side would simply be headlight.

maylar · Jan 25, 2020

I used a 3 position switch for a while and wired it such that the pilot lamp could be used as a daytime running light without the headlight. I had a 20 watt halogen bulb in it. With an LED headlamp (30 watt) that's not needed any more, so I replaced it with a 300 lumen LED bulb and rewired to stock with a 2 position switch. The pilot (parking) bulb is on whenever the ignition switch is on lights mode.

L.A.B. · Jan 25, 2020

marshg246 said:
Whether two- or three-way, the headlight toggle switch has 8 possible terminals. Some terminals are left off each type. AFAIK internally they all work the same.

I believe the original Norton 34660 switch has no internal connection between terminals 5 & 7 although the current ~~35710~~ 31780 replacement (as 34660 is no longer available) does.

34419 is a three-position switch (commonly used on Triumph twins) where 1-3 are connected and also 5-7 but not 3-5. Edit: This switch allows only the parking lights to be switched on when the ignition (two-position switch) is switched off.

marshg246 said:
On a Norton, normally, one wire goes to 1 (or 7) the other wire goes to 8. If you want it backwards, and you have a new "Genuine Lucas" two-way switch, you connect to 1 (or 7) and 6.

Not '1' on a "genuine Lucas two-way switch" (34660) as that has no terminal 1 spade, only 5,6,7 & 8 therefore it's 5 - 6 or 7 - 8.

Staytite · Aug 18, 2020

Gentlemen

About 200 years ago I bought a three position Lucas type toggle switch for my headlamp shell.

Although from a Norton supplier of parts it has no markings other than little raised numbers in the
black plastic next to the tabs.

It has 5 tabs numbered 1, 4, 6, 7 & 8. These are in the same position as those in diagram of marshg246 above.

Application of a vintage AVO meter (Set Number 1 MK3) pure joy has discovered

Toggle towards tab 1 = Tab 1 connected to 6, 7
Toggle central = Tab 1 connected to 4, 6, 7
Toggle towards tab 7 & 8 = Tab 1 connected to 4, 7, 8

From this I propose to connect :

Lights feed wire from ignition switch to tab 1
Supply from tab 6 to side light in headlamp (side light on in toggle towards tab 1 and central position)
Supply from tab 7 to Rev and speedo lights (rev and speedo lights on in all three positions)
Supply from tab 8 to dip switch for dip and main beam (dip/main on in toggle position towards tabs7&8 with side light off)

Which leaves no use for tab 4. As I am rather partial to the number 4, not utilise it seems a shame.

Appreciate any opinions on my logic

maylar · Aug 18, 2020

What functionality do you hope to obtain, and what vintage is your Norton (3 or 4 position ignition switch)?

Staytite · Aug 18, 2020

Hi Mylar

It's a sort of 1974, but with choice bits from several different years

It has a 4 position ignition switch, but withnothing attached to which ever terminal feeds the parking lights for the "reverse" position of the key.

Functionality required is for lights to work, as in side/rev&speedo on one toggle position and dip/main/rev&speedo on another.
The rear/brake lights are fed from the ignition switch.

Am I missing anything?

Thanks

maylar · Aug 18, 2020

A 74 with 4 position ignition switch only needs a single set of terminals (on/off) in the headlight. The power to instrument bulbs, tail light, and headlamp pilot come on in the "ignition and lights" position. The headlamp switch only turns the headlight itself on/off (it sends power to the hi/low toggle). That's stock wiring - if you're looking to do something custom you can use other circuits on that switch.

For example - I ran a 20 watt halogen bulb in the pilot bulb in my headlamp as a daytime running light. I wired a 3 way switch to allow turning the pilot bulb off when I wanted the headlight.

Dunno if this helps... there are wiring diagrams here - https://granttiller.com/

guest76 · Aug 18, 2020

It sounds like what you are doing is similar to the way the pre-71 three position light switch is wired up

Headlight Switch Wiring

WEM

L.A.B.

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Tornado

Richard Tool

WEM

Tornado

L.A.B.

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maylar

L.A.B.

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maylar

L.A.B.

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Tornado

marshg246

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L.A.B.

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Staytite

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Staytite

maylar

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