Scooterotica

Daft sounding electrical question but I'm at work, my multimeter is at home and I don't want to mess about for too long in the dark.
I'm pretty sure it's either a short or a bad connection but WHERE?
Simplified electronic loom, key ignition switch, GP light switch.
All lights work fine on second key position (town lights).
On third key position main and low beam intermittant, the town light goes on and off with them but none of the other lights are affected.

Help!

When i had those symptoms it was a poor quality keyswitch.
But there may be a different fault in this case...earth, connections etc.