Cable query (1965 B40F)

[Phil C]

Evening all, 
Electricity is not my strong point, but anyway I've just replaced a damaged cable between my horn and my stop light (replaced old-style 14/0.3 cable with a thin-wall 32/0.2, which I assume is okay?) When I'd done that, I thought I'd just get the muck and grease and insulating tape off the various cables in the battery compartment. I was cleaning the cables with a bit of degreaser and blue paper, when I noticed one bullet-ended wire hanging loose near the bottom of the compartment, so I put it back in where I thought it was from (can't remember which wire or where - kicking myself now.) I then noticed another loose wire, with a bare end, hanging down below the battery compartment. I guess I must have accidentally pulled it loose. It looks to me (see photo) as though that bare-ended wire has come from vacant snap connector near the alternator (but don't know why the wire is bare rather than having a bullet on it.) But what is especially puzzling me is that there is a double bullet connector with one wire going into it at the alternator end, and two WG cables coming out at the other end. Other wires coming from the alternator are a GB and a GY. (Ignore the small lengths of other colours, which I think must have been put on at some stage to lengthen cables which were too short.)My wiring diagram shows three wires coming from the alternator: a GY, a GB, and a WG. What I'm wondering is why one of my wires (can't tell the colour as so little of it is visible) comes out from the alternator, into a snap connector, and two WG cables come out of the other side. So I appear to correctly have the GY and the GB, but instead of one WG I have two.  Why would that be, and where do they go?
Tomorrow I guess I'm going to have to follow them to see where they end up, but in the meantime any ideas please? Any thoughts would be much appreciated.   Phil.      PS with a double snap connector, are all four points in contact with each other?

[Blackthou]

Hi,

I had a almost the same problem with a C15 I've  just bought and virtually in the same area. Wires were taped and unconnected, in addition the lights were very dim. It wasn't much better in the headlight. Everywhere was years of meddling to get a quick fix. I decided to buy a set of bullet crimps, bullets and connectors and methodically work my way through things cutting off modern crimps and replacing poor wiring and re crimping everything that had been fiddled with. The hardest part was understanding the logic behind the wiring and circuits. I found a copy of the wiring diagram and studied it but found I only uderstood it when I made notes. Understaning it was the key as opposed to trying to follow it

Over the course of a few hours, over a few days it didn't seem a mystery and I got everything working. Made sure I had really good earths. Now the horn and stop light work and the headlamp almost looks like LED in comaprison. I hope that helps in principle.

Good luck

[JulianS]

Double connectors all points in contact.

I suspect your wiring should be like or similar to the one below, you can see the WG connections indicated by the red arrow.

[Phil C]

Many thanks Blackthou and Julian. Blackthou's reply gave me (much-needed!) encouragement, and Julian's was a revelation!  I've spent ages this evening looking at my wiring diagram and trying to fathom what on earth the second WG wire could be. My diagram shows one WG going from the alternator to the rectifier. No sign on my diagram of a second WG nearby. But Julian, you clever old stick, the diagram you attach shows one WG coming away from the alternator, then soon becoming two WG, one of which goes to the rectifier, the other to the light switch (if I'm reading it right.) I wonder, is the one to the light switch is to do with controlling alternator output? Would that be true or not? So anyway the diagram you very kindly sent is different from the one I have, and yet mine is entitled "Wiring diagram for 1958 to 1966 'Star' models", which I'd have thought made it right for my bike (1965 B40F.)  What's going on, I wonder. Makes me doubt the rest of my diagram, even though its heading suggests it's the one I should use. I'm absolutely chuffed that I'm no longer clueless about the second WG wire, but confused about which is the right diagram.  I mean, will the one you sent be right for all the wiring on my bike, or just the wires I was confused about earlier this evening?   Phil.

[Blackthou]

Pleased to see you have renewed enthusiasm. I've read that the light switch does indeed play a part as you suggest. Keep folowing the logic until it makes sense. Worked for me and gave me the confidence to sort it out.

Top marks as always to Julian. I haven't been on here long and he's sorted me many a time. Thanks Julian.

[JulianS]

This factory bulletin from January 1965 may explain a bit about the extra WG wire. It is for the original 6 volt circuits.

[Phil C]

Absolutely brilliant - that explains it! Thanks very much, Julian.
I think I'll do away with the two short odd-coloured wires which connect to the GY and GB, by using slightly longer GY and GB wires. The short bits were, I imagine, just there to make up the length. I would also fit slightly longer WG wires, in order to do away with the short wire there also, but I suspect that disconnecting the WG wire from the light switch might not be easy ( I think they were fixed permanently and to make any changes entailed buying a new switch unit?) By the way, I plan to use 28/0.3 wire for all this - that's okay, isn't it?       Phil

[JulianS]

The early models were wired directly into the switch. The later models, like yours, the wiring harness attaches to the switch with a socket.Not easy to replace a wire in the socket. Designed to be made rather than remade.First photo shows back of a socket for the ignition switch (have not got a photo ofthe light switch socket). The light switch would be similar. Second photo shows the back of the later light switch showing the pin connections of the socket.

Some wiring harnesses have the 2 x WG joined at the rectifier you may find that you can reroute wiring without touching the connections in the switch/socket.

[Phil C]

Let me check I've got this right: if at the moment I have a WG from the light switch to the double snap connector near the alternator, I could remove that and replace it with a WG going from the light switch to the rectifier, connecting at the same point on the rectifier as the other WG which comes from the alternator, so that rectifier connection would have two WG wires going to it. Is that right?     Phil

[JulianS]

That is correct. You can joint the WG from switch to any point of WG from alternator to rectifier.

Wiring diagram below for a single with different switch set up but same principal.