Tracing an electrical leak - headlight

[the-chauffeur]

Strange one, this.  I seem to have some sort of power leakage from the lighting circuit on my K2.

With the lights off, everything's pretty much normal.  Turn on the low beam (mine's a European spec bike which has a pilot bulb as well as the main bulb) and everything's on as it should be - but there's a very dull glow in the high beam idiot light.  Fortunately, it's so dim that you only know it's there if you're looking for it - so MOT's and so on are no trouble.  There don't seem to be any signs of power drain/loss, but I can't seem to get the lighting circuit to close so that the low beam is on without there being a tiny current to the high beam idiot light.

I've tried pulling the loom about a bit and from what I can gather, it's not the high beam circuit that's the problem (or at least, not directly).  It seems that the idiot light glows when the low beam feed is connected to the headlight bulb.  Remove the low beam power feed from the headlight, and the idiot light goes dark - switch onto high beam, and both the beam and the idiot lights come on as they should.
 
This kinda suggests to me there's something hokey going on with the way the circuits are grounding (or not), but I can't work out where to start with fault finding because, like I say, there's nothing else wrong with it.

Any thoughts/suggestions?

[K2-K6]

I'd start where you have mentioned, the grounding for the headlight bulb.

Try running a seperate earth from the headlight bulb plug back to the battery to see if the main beam indicator goes dark.

As an indicator of what is happening, have you seen sometimes on old cars when they indicate and all of the lights on that rear panel also go on and off? that's usually a poor earth with the load tracking out through the other bulbs trying to get to earth. You only have the beam indicator as a route out if you've got a poor earth on your lamps so that could make t glow.

[Bryanj]

It's a grounding problem, part of the power is going via the main filament and idiot bulb, could be a bad bulb

[the-chauffeur]

Hmmm . . .

 . . . after checking out every wire and connection one at a time (inc. opening up the handlebar switch) I still couldn't stop the glow of the idiot light.

That was until I worked out that I had the three main wires to the bulb connected round the wrong way.  Not sure how, exactly, but swapping them round has put everything right.

D'oh.

[K2-K6]

Aah, at least you've got it now, seems like it's gradually getting sorted.

Ready to enjoy during the summer, usually comes in May and finished by begining of June!