Mysterious Grey wire

Hello Gents,

Can anyone tell me what this grey wire is for on the r/h switch block on a MK3 850?

It does not appear in the wiring diagram and the only grey wire I can see on the factory diagram is for the Neutral switch- (which is green on my bike!) The grey one, seen snipped out below, doesn't appear to affect the functions of the r/h switch block (kill, start buttons and head/pilot switch).



All thoughts welcome!

The grey is the power feed to the starter button (white/red out).


Perhaps the switch has been modified internally if the starter button works (maybe a jumper off the white wire-which is how it's drawn on the wiring diagram with 5 wires leading to the switch instead of 6).
A look inside the switch housing should answer this.


The grey wire on the 4-pin switch plug connects to the second white wire of the 4-pin harness plug.

Also...

You may also find the L/H switch assembly has two separate blue/white [UW] wires (one for main beam and one for headlamp flash), but the wiring diagram shows them joining together before they reach the multi-pin plug which doesn't appear to be correct.

Thanks LAB, that's very helpful.

Strange indeed then that the starter button still works- and hard to imagine why a PO would 'modify' things like that. The whole reason this came up is because I've bought a new Sparx r/h switch and it doesn't include this grey wire. My o/e switchblock has the head/pilot knob knocked off. I'd never bothered about it before because it is set to 'Head' and obviously the ignition switch is used to turn on the headlight. But I now want to run an LED in the Pilot as daytime headlights, in a bid to reduce the load on the charging system.

Thanks for the pointer about the l/h switch. I think the headlamp flasher is applied by pushing/flicking the horn button upwards? Do you think these o/e multi pin connectors are worth persevering with or is there a better/easier/cheaper/more waterproof modern alternative?

Lastly, I have been meaning to ask what is that extended points cover on your avatar? Dare I say it, I'd love to see a picture of your MK3.

(I sometimes think on this forum we should organise a photo gallery of members bikes by model- and then also the modified ones (which are may be even more interesting!)- it could be a good reference source-but I guess where to draw the line over standard/modified would not be straight forward as nowt is absolutely as it left the factory 40 years ago!

Many thanks!

crusadersports said:

Strange indeed then that the starter button still works- and hard to imagine why a PO would 'modify' things like that. The whole reason this came up is because I've bought a new Sparx r/h switch and it doesn't include this grey wire.

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Yes, it does seem to be a bit of a waste of wire having two independent power supplies to the switch cluster-when a simple internal jumper wire would have been more than adequate and that is what's drawn on the wiring diagram.

crusadersports said:

Thanks for the pointer about the l/h switch. I think the headlamp flasher is applied by pushing/flicking the horn button upwards?

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Yes, push in for horn, and up for headlamp flash.

crusadersports said:

Do you think these o/e multi pin connectors are worth persevering with or is there a better/easier/cheaper/more waterproof modern alternative?

Click to expand...

There are certainly better options available.

crusadersports said:

Lastly, I have been meaning to ask what is that extended points cover on your avatar?

Click to expand...

That is the Lucas Rita pickup cover-which was on there when I bought my Mk3 (although it actually had a Boyer fitted, and now it's got a Tri-Spark) and I've never bothered to change it.

crusadersports said:

Dare I say it, I'd love to see a picture of your MK3.

Click to expand...

Although photos of various parts of my Mk3 have been seen here on numerous occasions-I admit I don't really have any good photos of the complete machine so this one will have to do for now.

crusadersports said:

(I sometimes think on this forum we should organise a photo gallery of members bikes by model- and then also the modified ones (which are may be even more interesting!)- it could be a good reference source-but I guess where to draw the line over standard/modified would not be straight forward as nowt is absolutely as it left the factory 40 years ago!

Click to expand...

This subject has cropped up before-but Jerry has never seemed to be too keen on the idea in the past. If members want a photo section then they will have to ask Jerry.

My MKIII also has a snipped wire in the rh switch gear. I don't remember the color off hand, but I believe it is because mine has the Canadian Lights Control Unit which prevents turning off the headlight with the bike running. It means the pilot/head switch does nothing so I believe the factory probably snipped this wire coming out of the switch gear.