Side lights wont turn off!

[confused.com]

Hello everyone. I hope this is in the correct forum, and hasn't been discussed before! I did a search but came up with nothing!

My girlfriend has a Toyota Yaris Saloon year 2000, and tonight the side lights (front and rear) wouldn't turn off. I thought it must be either - a relay (if one was even needed for the sidelights, which I doubted) or the light switch itself.

I pulled relays out one by one, nothing. I then pulled out fuses. When I removed the 50A one under the dash, the side lights (front and rear) went out. Here is where it gets very strange though. The light switch still worked as normal with the fuse removed (first position side lights came on, second dip, pull/push main beam), BUT when the light switch is in the OFF position, no dash lights, radio, or digital display work!

When turning the light switch to the first position, they all come back on!

So is there another relay hidden somewhere, or have missed something very obvious?? This seems like a very bizarre fault...

Any help or suggestions with this would be very much appreciated!

Best wishes and thanks in advance!!!