Headlight issues

[Addzz]

Small update, my eastern beaver kit has arrived and looks well made.
Have not been able to try and get to the bottom of the issue due to working 7 day weeks and then all the rain we’ve had recently (no garage to work in  )
But I was back early today so went out to run it up as it’s not connected to a maintenance charger and lo and behold the full beams are now working!

Will still lift the tank and air box when I can to try and ascertain what the flip is going on

[Addzz]

Just to update this and yes I know it’s been a while but life just gets in the way sometimes.

Tested headlights and had no hi or low beams, no relays clicking, nothing! So tank and air box etc off. Took the yellow connector apart, a little bit of corrosion but cleaned up OK with some contact cleaner. Then the lights worked again putting the air box back on the lights cut out again.

So air box back off again, wiggled the yellow plug and the lights came back on again.

So you clever blokes were spot on with it being the yellow plug.  Pulled a couple of the pins out and more corrosion and a couple of connectors just about hanging on to the wires. 

I’m going to cut out the connector and fit a new one

[Gert]

At best of times, electrical faults can be a pain in the backside to diagnose on most vehicles. Well done in finally diagnosing the cause of the high beam failure on your bike.

[Addzz]

Well I possibly jumped the gun a bit there.  Replaced the yellow multi plug one wire at a time to make sure I got them all correct and again no hi or low beam headlights.
I have horn, left and right indicators and the hazard lights all work

Could the starter switch be playing up as well?

[purplebikeunicorn]

Could be. If you've had the wires out, check the fuses are still all intact. Also check that the wires have been correctly "clicked into" the connector as if they're not, they'll push them out when you put the connector back together with its mate.

[Gert]

The fact that both the high and low beams are no longer working, I would 1st take a test lead directly from the battery terminal to the headlight connector, to establish which leg / potential is not being supplied to the final point, which is the headlight bulb.
Once you have established which potential is missing, you can work consult the wiring diagram to determine the colour of the wire that you are tracing and follow up accordingly.
In my reply #12 I've included an edited version of the headlight circuit.

[Pete O Tube]

@Addzz when you say you've replaced the yellow multi plug one wire at a time, what have you actually done?
Have you cut out and replaced all pins and receptacles? or reinserted the existing pins and receptacles in to a new connector housing?