Horn/Lights wiring problem

[Bongoball]

Hi Chaps,
I need some help fault finding a problem.
Lights off, press the horn button and the sound is as it should be.
Lights on first position, press the horn and it is quieter.
Lights on position for dip and full beam and the horn is even quieter and dull.
When I did the nut and bolt rebuild, the frame was powder coated along with the handlebar clamps and headstock.
Could this be an earth problem?
How can I check this and what else do you suggest?
Cheers,
Bongo.

[Pigford]

Cold well be poor connection - earth

[z1bman]

leave the brown wire connected to the horn + disconnect the other wire. then short the the horn terminal to a good earth on the engine with a piece of wire + then turn your lights on to see if it changes the tone if the horn is constant it is probably the powder coating on the handlebar clamps or powder coating not cleaned from under the centre nut on the top yoke

[ADRIAN H]

Poor connection from switch to handle bar (which is the earth for the horn), is my guess.

[Bongoball]

Hi Chaps,
Thanks for your pointers.
I went through every connector under the tank, side panels, controls with switch cleaner to see if that cleared it.
Tried horn/ light sequence and it was better.
I did what you suggested z1bman and the tone was the same as wired normally so it must be the way it is.
Thanks again for the advice.
Cheers,
Bongo.