Yaris Horn Relay

[mekman]

Hello - the horn on my 2008 Yaris has recently stopped working. checked the fuse, and it was blown, so I replaced it with the spare. The spare didn't work either - so I removed it, and saw that now the spare fuse was also blown. I replaced it again with another good fuse, tested the horn (no luck), and then noticed the third fuse had now also blown.

I've been reading to check the horn relay but haven't had any luck finding where the horn relay is in the fuse box. I've attached a picture of the fuse box - is the relay in this box or somewhere else in the car? The fuse for the horn was where the empty slot is in the top row of this picture.

Any help appreciated - thanks.