Wierd Lighting problem - FIXED

I set out to go “the long way” to the branch meet the other day only to find that when I switched the head light on while both main beam and light warning lights on the instrument binnacle both came on the head light itself didn’t.
No matter how I fiddled with the dip, flash switches made any difference.

However, after riding for a bit normal service was resumed.

I can’t think what combination of switches/relays could give rise to that result

Anyone else experienced this?tris2014-08-10 19:01:31

It could be a loose connection or a short, not in the switch as that could possibly put both main and dip lights on but maybe in idiot light binnacle. Have you had the idiot lights apart recently?

Mhh - I have

Sounds like that might be a good place to start - cheers

Usually find that bizare and inexplicable electrical faults come down to poor earths/high resistance (power takes path of least resitance) and/or something simple like a “crossed” wire.
Best of luck

I would go with Steve’s comment, almost certainly the headlight bulb earth wire. I had the same thing and all sorts of wierd things were happening to the lights.
Always good to look at the last thing you did to the bike when things go wrong!

I concur. Headlight filaments are very low resistance so doesn’t need much of a bad connection to render them NOP.

I ran a new earth wire from the earth cluster point on the lower fork yoke on my T3 Cali to the engine. That sorted out a baffling and irritating issue of my “parking” light sometimes working and sometimes not.
All the best,

I had that too and did the same thing on my T3 Cali, that’s because the earth tabs inside the bottom front of the headlamp are crap after 35 years. Understandable really.

run a new earth,i had to do this on a couple of my bikes

Yes must not rely on getting an earth to frame through the steering head bearings. I’m surprised they’re wired like this at all. Even on my '76 850 I’m sure there was a separate earth wire to frame. Well there is now anyway 'cause of when I rewired it.
Mike H2014-07-31 12:37:11

Nice down to earth ideas there
I’ll get my coat,

Thanks everyone I’ll get on it ASAP

Fixed him!

If the earth wire in the headlight (that I changed a week or so back) drops off you get the problem I had

All better now - cheers all