Weird "electrical fault"?

[Sidk]

This morning a took the steamer out for a nice drive up the coast to the Temple of Poseidon at Sounion.. While riding there i turned on the lights at some point, and this caused the tachometer to drop to zero and all lights off as well as horn not working . when i turned off the lights the tach started working again.   

[John Stenhouse]

Battery not charging?

[Sidk]

No issues with battery. Bike turns over and starts fine.
I turned the lights on after about 30 minutes of continoues riding 

[London_Phil]

Water in relays behind headlamps?

[Mustang]

Water in relays behind headlamps?

1. start here ........................you have a dead short in the lighting circuit .

2. the other place to look is for chafed tail light wires .

then look at the switch if no joy with @1 or #2

[Sidk]

thanks for pointing me in the right direction... I will have a look at the taillight assembly as it is most likely some issue with the taillight assembly.  as i was having an issue with the brakelight recently.. so its most likely related and too much of a coincidence... 

[Sidk]

Just a follow up,

there was corrosion on the bottom wire/connection of the rear light assembly
cleaned and sorted and have not had a problem since.

thanks everyone

[threepot]

Had a similar issue with mine recently. Bike would act as if the kill switch had been pressed for a split second when I turned the lights on. Cleaned relay connections(London Phil),and acf50,and handlebar switch. So far it's been ok.