Mk2 wiring help needed

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Dedubyah

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I am getting towards the end of my engine rebuild on my new to me 850 and have installed a Pazon Altair and reg/rectifier however I never took the time to check all of the electrical functions prior to tearing it down, other than starting it. Firstly, the headlight and indicators weren't working and when I removed the rubber cover from the master switch, I found it only has 3 sets of terminals, which I read ,was only on the 1971. I have ordered a new switch but in the meantime have connected the power in (Blue/Brown) to the power out(White) but when I power the Blue/Yellow or Brown/Green, I see voltage when probed to the frame, also can anyone tell me which connectors fit where on the 3 way headlight toggle switch? Help appreciated, thanks.
 
Take pictures during disassembly, of everything. That gives you some basic form of starting reference.

Mk2 wiring help needed


Mk2 wiring help needed




Mk2 wiring help needed
 
Dedubyah said:
I found it only has 3 sets of terminals,
Click to expand...
To use the three terminal switch plug the blue/yellow onto terminal three with the brown/green.

Dedubyah said:
also can anyone tell me which connectors fit where on the 3 way headlight toggle switch?
Click to expand...
Should be a two position switch but connect blue/yellow to terminal four and blue to terminal eight.
andover-norton.co.uk

Andover Norton - LIGHTING SWITCH 2 POSITION 34660 LU31780 (LUCAS) - 06.8024

LIGHTING SWITCH 2 POSITION 34660 LU31780 (LUCAS)
andover-norton.co.uk
 
Thanks for that, with the blue/yellow on T3 I have power to the headlight terminals, the high beam light comes on, I have 5ohms from the headlight connector earth to the battery but no headlight (bulb lights directly from a battery). When I replace it with the blue/green, I have a tail light, the brake light works and when I probe to earth it shows voltage. Does this indicate a short to earth in the brown/green circuit? It hasn't blown a fuse. I have only a basic understanding of electrics so any help is appreciated.
 
Dedubyah said:
with the blue/yellow on T3 I have power to the headlight terminals, the high beam light comes on, I have 5ohms from the headlight connector earth to the battery but no headlight (bulb lights directly from a battery).
Click to expand...
Sorry I don't quite understand that, you say the headlamp circuit works then you said it only works powered by a battery?

Brown/green powers the tail lamp, pilot light and instruments. The brake light should work from white on T2.

If it hasn't blown the fuse then it's probably not a short circuit but I'm not sure what the problem might be if there is one.
 
I meant that the bulb is okay, I tested it with a battery. I have voltage to the two sprung contacts in the headlight connector and 5ohms resistance in the earth connected to it, but the headlight doesn't work. Perplexed as to why not
 
The headlamp shell connection is really a connection to ground (red) for the front direction indicators, it should not be considered a ground to the battery. If there are no direction indicators then the headlamp shell connection is redundant. The headlamp should have its own ground/red wire.
 
There should be a good return wire from the headlight bulb to the battery and from the horn button to the battery.
These are both quite high current devices, the horn is also inductive. If they try to return through the steering head bearings, it will cause pitting of the races
 
On mine the only intentional frame connection is the large battery cable to the starter motor fixing bolt. Every component is connected to a return cable. Due to the decision I made on the starter motor return, I'm using a negative earth, but it is of no consequence, I could make the engine cradle frame etc out of plastic and everything would work perfectly. Copper wire is designed to carry electricity, steel tube isn't
 
One thing you (everyone) should do is replace all the original single and double bullet connector sleeves especially the ones in the five way connector under the fuel tank as they become brittle over time. The latest type do not.
1771763626055.png


1771763746016.png

If necessary the five way block can be replaced with five doubles as there should be no internal connections between the circuits.
Mk2 wiring help needed
 
It has the original BPF headlight connector. I've been seriously considering making a new loom with spade and Deutsch connectors but will try running my battery earth up to the headlight shell in the meantime, thanks

Dale
 
Hi Greg, yes it has an earth wire to that connector which goes into a quad bullet connector, shared with the indicators.I probed that to the battery and 5 ohms resistance, I guess that's why the indicators don't work either.
 
I cut off all 4 of the (poxy) bullet connectors and joined them into a Wego, ran a 3mm wire back to the battery, headlight and one pair of indicators now work, progress...hooray.
 
marshg246 said:
I use WAGO 221 connectors and I completely eliminate the nonsense under the tank.
Click to expand...
I have gone for Wago 221 on my current wiring attempt. Fantastic for quick changes if I need to adjust the length of a wire or reroute. But I still get quite a lot bunching up under the tank. Can you share a photo please of under the tank and in the headlight shell with Wagos? Thanks
 

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